Allowing you to branch your base classes out into specialized varieties.
ie
ranger into bow or dual wield
fighter into sword/shield or polearm
paladin into defender or avenger
thief into burglar or assassin
Would affect what skills/abilities/spells you got or how good you are with them.
Tyris was talking to me about a similiar idea. he was even talking that maybe theres only like 3-4 base classes and then you choose a guild at a certain point. While that would be cool, it would also be a TON of work to balance that much stuff because your going to end up with 20 or 30 “classes” instead of 9. And we are already having some issues with balancing with just the 9 classes…