I've definitely noticed a trend in campaign design: There is a great Evil(tm) about to overtake the world, and the PCs are the only ones who can stop it ( possibly because they have The Choosen One (tm) in their ranks.. So, around level 20, they have the huge showdown with the BBEG, save the universe, get the girl ( or boy ), and live happily ever after on a legendary parallel with King Arthur in that campaign world.

The end of Critical Role, campaign one, certainly helped cement this in many peoples' minds as the way that campaigns are structured.

But I'm playing with the idea of having this not necessarily be the case.

My party is currently off plane hopping for the first time ( 7th level party ). They're escorting an emissary of a monastic order of Elemental Warlock/Monks through the dimensional gates, to attempt to retrieve an ancient artifact of great importance to the demi-god level founder of their order,  who was tricked out a McGuffin by a Devil overlord in the Hells. ( I'm kind of stealing material from Robert Heinlein's Glory Road if anyone's read it ).

This little quest - retrieve a sacred relic from the forces of the Hells - could be a major campaign in-and-of-itself, and if given the treatment it deserves, it should be.

But ... does it have to be the epic campaign of the Party?

It can be part of the Party's story, but it doesn't have to be the defining aspect of the campaign for the party - they can just be there for witnessing the beginnings of the Monks' epic campaign arc.

Essentially, I'm thinking of making them part of the "origin story" of a campaign that most likely won't be their campaign.

The end of the origin arc for the Monk Emissary will definitely aid the party in their current campaign arc - they'll get information and resources that they need for the quest they're currently on - but they will be given the option to walk away and return back to the prime material plane - possibly now with new allies ( the Monastic Order ).

What do you think? Do you think that a typical party would feel cheated by this kind of approach? Do you think that they expect to be the sole spotlight in the universe you're creating?

I know you don't know my party - but I guess I'm wondering how most players would react to this.

Yea, most people want to be the most prolific thing to happen: "I spent 4 years playing this character, I better be heralded in like Luke and friends at the end of the movie."

However, if you can spin the tale to herald them as the primary reason that the ending happened in a particularly good way, it may work. You guys did all of this work, put years into your game, invested all that time into your characters. When the King ascends the throne he better tell the players' characters that they'll be remembered as stone statues where all can see. The monastery will erect a temple for each of them and dedicate teachings based on their actions. Something to show that their actions will provide them with a legacy that transcends their character sheets. Something of that caliber should elicit the same, or a similar, sense of accomplishment as "you rescued the princess, good job".

Edit: As an aside, they're in the spotlight for almost the entirety of the game. Just because they can watch someone else walk off into the sunset doesn't mean the sense of accomplishment will be diminished. 

Oh - I'm not making this the end of their campaign, where it turns out they're not the heroes after all.

I'm not that cruel :)

I guess I'm playing with the idea of" "there are multiple epic campaigns in the world. Some of them are even connected together in a larger tapestry of greater world events. You're not the centerpiece of all of them, but your campaign is your particular story. But while you're the primary characters in your story, you can be secondary characters in others".

The player's characters should be the prime heroes of your campaign. It's not fun to be over-shadowed by some other hero group (that's only funny in comics). 

However, that doesn't mean that the players have to be the ones to save the planet. Saving the town, defeating the big bad, rescuing the princess. These things aren't world shaking, but they can  easily be the climax to your campaign.

Sure - like I said, I'm playing with the idea that there can be many heroic threads in the story ongoing in the world.

The players are still the heroes of their particular thread. Whatever campaign goal they have, they will be the one to accomplish their task ( or walk away, or die trying - their choices, their fate ). 

It's kind of like, they win their battle, and are the heroes of that battle. That isn't contested.

The war, however - that's a cooperative effort. Other battles, other heroes - all pool into final victory. 

Or are you saying that you believe that the player characters need to not only be the heroes of their particular corner of the campaign world - but they need to be head-and-shoulders above everyone else, globally. It doesn't matter if the primary crisis in the world is world-threatening or not - but they have to be the best heroes anywhere?

First amongst equals doesn't count?

Not sure Critical Role cemented this in people's minds. Just look around you at overall societal behavior. Look at how other entertainment media are handling this power fantasy. In video game design power fantasy is just too extreme in my opinion. You overpower everything very fast and then it just keeps getting worse and worse. It is what everyone expects things to be. It is part of the "entitlement"-culture that is going on for years now. This is also why my friends and I came to D&D and wanting a more gritty and "realistic" experience.

This meant that my players are NOT the heroes of the world. They're not seen as such and are nothing more then just a cut above the average. Strong enough to set out adventuring and make a name for themselves. However there are other adventuring parties as well that the group gets compared too. This can lead to its own motivating for the group to reach for new heights and become "celebrities" of sorts. The world doesn't revolve around the players and will not be passive/reactionary to them. People in the world have their own motivations and goals that they work towards. Whether the party wants to get involved is up to them. This also aids to cement the more "realistic" nature of the game.

Once they've beaten Tiamat's aspect they eventually get approached by a contact of the Harpers. "hey we've heard of your exploits dealing with this event. well we got similar trouble up north. You've beaten only one cell of the cult of the dragon. there are others and we're looking for multiple qualified groups to aid us in this". Once they arrive they'll also hear about another adventuring party that pretty much dealt with the situations prior to Rise of Tiamat in Horde of the Dragonqueen. I really cement that my party are not the only ones and they're not the best (yet) either.

In the end however the power fantasy will still come through. By then, in my opinion, they've earned it. Plane hopping and having accumulated lots of power and wealth... its only normal that they're the top ranked adventurers of the realm. At lvl15+ it is fair too assume they're the best the world currently has to offer.

D&D gives players access to godlike powers when you reach higher levels, that almost demand them being the heroes in world shaking events. Other systems give a lot less power to the player characters (including not having e.g. travelling to other planes).

High power campaigns get problematic for me, when the world's development purely depends on the player characters and does not evolve or change without the heroes.
In my campaigns (all self made, I haven't played a module in 30 years), there are usually story three paths of progression happening at the same time. If the players chose to be involved in path 1, path 2 & 3 will continue to shape the world. In a second stage, the players can get involved in a new path one (2 & 3 will resolve without their interference) or they can hop on to the path 2 or 3 which are already developing. This means that one story path will always be resolved without the player's involvement (not taking action on two consecutive "turns"). The event paths are usually tied to an NPC, organization or event. Should the players not care about the mob boss and his thieves guild in their home town, because they chose to hunt for a hidden treasure in a tomb and participate in a big social event at court, the NPC will be a lot stronger (e.g. having leveled up twice as fast and his criminal organization has grown a lot).

Of course this is no means against Chosen One PCs (*eyes Fjord in CR campaign 2*), but at least gives the DM some control over the rest of the world.

I think you're correct in that the godlike powers of higher levels may be the incentive for world-shaking events with the party smack in the middle of it all - and may require something of that scope.

When everyone's a Gandalf, you need Sauron and the War of the Ring to be a challenge.

Still, imposing a level cap on your player's to keep the powers 'reasonable' would likely result in Player revolt - and rightfully so, if that's literally not what they signed on for.

I think that the godlike powers, and the narrative structure, might be baked right into the Heroic Fantasy aspect of D&D. Which makes me wonder about other systems - perhaps one needs to accept that this is part of D&D and perhaps dabble with other systems which are more oriented to sword-and-sorcery than epic heroic fantasy ( you know, with all my other spare time ... ). However, this raises the issue of how trivially easy it is to find Players for D&D ( good Players ... another story ), and the near-impossibility of finding Players for a different system ( "but ... I watched Critical Role ... let's play that" ). 

I may just be trying to bend 5e into shapes it was never meant to fit into - and I do bend the system and my campaign into some weird shapes, largely because I don't think I'm particularly happy with ( what I perceive as ) adolescent power fantasy based on a collection of 40-year-old fantasy fictional tropes that every player memorizes within a year or two of picking up D&D  ( I literally had an Player trying to deduce what class an NPC was last session, based on the spells they saw them use ). There's absolutely nothing wrong with the classics, just as there's nothing wrong with mac-and-cheese - but variety is nice as well.

In my campaign I have the players pseudo-following in the footsteps of a different adventuring party, the legendary heroes known as The First, who saved the world from a demon incursion long ago and whose impact can still be felt. The players are still the heroes of THEIR story, and since they are the ones playing the game, that story takes precedence. But it’s easy to thread in multiple different epic characters and NPC arcs.

One of my players’ favorite characters is a budding young cleric who desperately wants to be an adventurer of her own, who they sort of took under their wing for a time - you can be damn sure the characters will get some satisfaction when they finally see her out adventuring!

I rarely GM but as a player, I don't find it necessary for the universe to revolve around the PCs. In fact, I often find it annoying when the PCs are the center of the universe. 

Too often I find that the PCs are treated as the chosen one without directly saying it. They are asked to do something that skips right past dangerous and jumps straight to objectively suicidal for a group of 4-6 people no matter how powerful and they are expected to accomplish this task on there own with effectively no support from those who gave them that mission, even when it would make sense to send more people. Or that the PCs are the only possible way for a positive outcome, any event in the world that the PCs are not directly involved in will automatical result in a loss for the good guys, which makes everyone else in the world who isn't the PCs or villain feel incompetent or impotent, which makes me question how they weren't destroyed sooner and makes me wonder if we're better off with the villain in charge they at least seem competent. Basically, most games seem to have the expectation of "you will do this because you are the heroes", as opposed to "you are the heroes because you did this".

In a game that I am currently playing in the GM managed to get around this problem while still allowing us to be the heroes by making us apart of much larger events and not having us specifically chosen by the quest giver until we earned that attention and even when we are, were not the only people they could send to accomplish a particular mission.

The quest was to investigate threats to the kingdom from a county to the north beyond a vast wasteland with the promise of rewards based on what the groups discovered.  It was being offered by the local government and was not given to us directly but was handed out to pretty much anyone and everyone who would take it, thereby not making the world revolve around us. As opposed to most quests where the PCs would be the only ones given the quest despite it being impractical to give this assignment to only one group.

While on this quest we encountered a side quest which was to save a town that been taken over by you standard tentacle horror and its minions. In most games, I have played the scenario would have gone something like this, The PCs find a group of starving survivors who say they no one for them to turn to for help except for the heroes so they beg the heroes to slay the monster and free there town. The survivors have no food, no supplies, no warriors and no way to support or incentivize PCs but you are expected to save the town anyway when would it be easier to abandon the town and relocate the survivors. In the scenario that we played, we encounter an organized resistance group made up of survivors from the town and some other adventurers who were planning an assault on the monster and his forces in a couple of days whether we decide to help or not if we did decide to help we were offered to either distract the monster's minions while others attacked the monster or to attack the monster directly and were told that the monster had been collecting all the treasurer from the area and if we join the assault on the monster we would have first dibs on the treasure. It didn't feel like they would automatically fail if we chose not to get involved just that they had a better chance of success if we helped. We chose to help and joined the attack on the monster, while on the way into the monsters stronghold the other adventurers were engaged my the monster's minions so when we finally engaged the monster it was just us and the resistance leader fighting the monster. We succeeded and were honored as heroes for slaying the monster. The events were going to happen whether we helped or not and the outcome didn't feel like it hinged entirely upon our actions, we were not the center of the universe and we were the heroes because of what we did, we didn't do it because we were the heroes. It felt much more natural.

Give your PCs some support and incentives to accomplish a quest even if the support and incentive end up being a nonfactor in the ultimate outcome and have events happen whether or not the PCs get involved, also make the outcomes of the events that they don't get involved in not always an automatic failure. They can be heroes but the world doesn't need to and shouldn't revolve around them.