It would be nice to have a new class to play after you get lvl 99 or just when you are a bit experienced in the game, so I tought that there should be a new "subclass" for every class.
Paladin(warrior) that would have a broadsword(mix of the sword and the axe)/axe/etc. and a shield(like the warrior's shield)/healing statue(Yes, this idea comes from another post I made, so yes, you could again place the statue in the ground to heal your hireling while you attack ennemies)/etc.
Assassin(rogue) that has to drain their enemy's life by "backstabbing" and then flee with teleportation or sprint.
Mage, I am lacking imagination, but it could probably be a cleric, I don't know.