You are seriously asking if the collective imagination about what classes can be is exhausted.
Come up with a neat idea, independent of class, and then figure out which class it fits into best, and what sort of tweaks would be required to add the new powers and balance it.
Does it sound like a Fighter archetype? Will you give up Weapon Training? Armor Training?
You have the power to mutate any class into exactly the sort of experience you want to play.
A fully-Divine Bard?
A Ranger that loses his Bond and gains something like a Paladin bonded weapon?
A Monk that gets Abundant Step early, and gets Dimensional Dervish related feats for free at set levels in place of bonus feats.
You can (and should) also tie in lore or locations, especially with the focus on the River Kingdoms.
Will you make a bandit-like archetype? How will it be different than all the Rogues out there?
Razmiran is right on the border of the River Kingdoms, and the flavor/fluff there is fantastic.
Obviously, it has to fit in with the setting, and some of those examples already exist, but I'm just trying to convey how free form it all is.
You are only limited by your imagination here.