So after they dropped the draconic options UA, combined with the previous Drakewarden Ranger/Dragon Soul Monk, we're definitely getting some official dragon-themed content on the horizon. My gut tells me this isn't all Dragonlance related because the content we've got so far has been largely setting-neutral (which I'm fine with), but I was wondering; what other dragon-themed subclasses do you think we might see in a Draconomicon-type book? 

Some ideas I've seen floating around so far include: 

-Dragon-Oath Paladin; embrace the dragon-slaying knight archetype

-Dragonrage Barbarian; sure I guess, you can really combine any word with "rage" and get a barb subclass out of it.

-Dragon Pact Warlock; strong option, I'm actually kind of surprised we don't have one yet. 

-Dragon Druid; sure why not

-Dragoon Fighter; anyone remember Legend of Dragoon? Not that I expect them to lift that concept from an obscure cult ps1 classic, I just love that game. Final Fantasy dragoons would probably be a more contemporary influence if they were to do something like this, with a fighter that draws on draconic power to fuel cool combat maneuvers. Could also see the paladin oath being "oath of the Dragoon" or something I suppose so it doesn't *need* to be fighter.

Any other cool dragon-themed subclass ideas? 

Is this about stuff we might actually see, tempered by things like how WotC has implemented stuff in the past, or more about dragon-themed ideas of our own, without worrying about that?

If the latter, I'd love to see the Artificer subclasses in Tasha's expanded on with options clearly intended for compatibility with dragons, regardless of any new Artificer subclass.

I'll do an example for all of them:

Battle Smith:  Optional Feature:  When you create a new Steel Defender, you may infuse it, rather than spending infusions the normal way.  Each infusion can add any of the following features:

• Retractable Claws: The Defender's Rend may deal Slashing damage instead of Force.  The Defender gains a climb speed equal to its walking speed, and may add the Artificer's proficiency bonus to its Strength, to a maximum of 20.
• Submersible:  The Defender's Rend may deal Bludgeoning damage instead of Force.  The Defender gains a swim speed equal to its walking speed, and may add the Artificer's proficiency bonus to its Strength, to a maximum of 20.
• Aerial:  The Defender's Rend may deal Piercing damage instead of Force, but regardless of type, its Rend damage die is reduced to 1d6.  The Defender gains a fly speed of 40, but loses its walking speed.  The Defender's hit points are reduced from being based on 5*Artificer level to 4*Artificer level.  The Defender's Strength is reduced to 7 (-2), but it becomes Large.

Artillerist:  Optional Feature:  When you create a new Eldritch Cannon, you may infuse it, rather than spending infusions the normal way.  Spend an infusion, and pick a draconic damage type (Acid, Cold, Fire, Force, Lightning, Necrotic, Psychic, Radiant, Thunder); the thrower and the ballista use that damage type instead of fire and force, respectively, and all three cannon types are immune to that damage.  If a cannon has one of these infusions, it may swim rather than walk or climb.  If it has two, it may fly, and if it has three, it may hover.

Armorer:  Optional Feature:  While an Armorer's armor has an infusion in it, any non-humanoid mount the Armorer is mounted on is proficient in all types of barding.  An Armorer gains the following infusions, which only work on parts of the Armorer's Armor:

• Thunder Lance:  Guardian Armor or Thunder Gauntlets only.  The thunder gauntlets gain Reach.
• Lightning Bolt:  Infiltrator Armor or Lightning Launcher only.  A creature that suffers the Launcher's additional 1d6 damage must also make a Constitution save (DC the Armorer's spell save DC) or be paralyzed until the beginning of the Armorer's next turn; at the beginning of its turn, it may also attempt an additional save to shake off the effect.
• Spurs:  Either Armor or its boots.  The Armorer may spend a bonus action while mounted to grant their mount the ability to bonus action dash or disengage.
• Dragonhelm:  Either Armor or its helmet.  While worn, the Armorer is proficient in Draconic, and has advantage on Intelligence, Charisma, and Wisdom checks when interacting with Dragons. 

Alchemist:  Optional Feature:  You can infuse a bottle.  When you create an experimental elixir in a bottle with this infusion, choose its effect - you do not need to roll.  You may also choose from additional effects:

• Choose one Draconic breath damage type (Acid, Cold, Fire, Force, Lightning, Necrotic, Psychic, Radiant, Thunder) at creation time; the drinker is resistant to this damage for ten minutes.  In the cases of Poison and Necrotic, they also have advantage on saves vs poisons and diseases, respectively.
• Choose one Draconic breath damage type (Acid, Cold, Fire, Force, Lightning, Necrotic, Psychic, Radiant, Thunder) at creation time; the drinker is immune to this damage for one minute.  In the case of Poison, they are also immune to the Poisoned condition and all poisons.  In the case of Necrotic, they are also immune to all diseases.

I'm not so much speculating on what I actually think might be in the book, and more just wondering what kinda stuff people think it would be cool if it was in the book. 

I think you covered most of them, except maybe a Dragon Domain Cleric subclass (it was a thing in previous editions). I personally want a Dragon Fighter and Dragon Warlock more than any of the others, but a Dragonrage Barbarian would also be cool. 

I have created some cool subclasses that are dragon-related...

1. Bard: College of Drakesingers (Sing and Dance in a Draconic Way - it's odd to hear but should be fun to play)
2. Rogue: The Dragonslayer (Rogues who adopt draconic elements within themselves to hunt dragons)

Also, I'm betting the upcoming book ain't dragonlance, because of the Fey - IT'S A NEW MONSTER TOME!!!