Oops! All Fighters

Quote from Sanvael >>

There's no reason that they'll die, but it will be a fairly dreary campaign since they have few options. With no Cleric or Paladin they cannot use the Symbol of Ravenkind, and will have a really limited set of abilities to deal with problems in interesting ways. Moreover, they'll find that most of them rarely get to feel special, since everyone else can do what they do.

I'd tell them that there are five Fighters in the party, and ask them whether any of them would like to change class. You may well find that several of them are happy to switch to another class. Mention to them that in order to have moments where they get to shine, it will probably be more fun if there is a range of classes. I think you'll find your players are happy to reevaluate their choices.

Alternatively, ask them to rate how much they want to play a fighter over any other class, on a scale of 1 to 5. On a 4 or 5 they keep playing Fighter. On a 2 or 3, ask them to consider changing. On a 1, tell them that you'd appreciate it if they changed class. If everyone chooses 4 or 5, then let them run an all-fighter party. If you think they're finding it a bit grey and some of them want to change mid-campaign, ramp up the difficulty of encounters to a near impossible level and let 2-3 of them die off early.

 One or more could multiclass, fighter paladin/fighter cleric can work well. 

Some fighters can use magic (EK subclass), and some fighter builds actually work as archers (dont underistamate +2 to ranged attacks from archery fighting style).

Your party could work depending on what other options (race, backround, soon subclass) your players take.