How can they add more classes and make them unique and have their own flavor?

[Lambdafish]

Different playstyles and good game design. New DPS are easy and will just DPS using a new mechanic (mudra for example). It's tanks and healers that are more difficult, as they need to be balanced the same, and there arent many new niches to be filled (tank has room for another main OT, but I'm not sure what function that would take).

Of course SE could be really ballsy and do things like tank pet, and melee healing, but I really don't know how those will work.

examples off the top of my head (not balanced or thought too hard about):

RDM: melee dps - acts as a magic counterpart to ninja, with elemental INT attacks, and lots of magic utility like reflect, virus type effects and vunerability ups

CHM: healer - think of mix as healing ninjitsu

SAM: melee dps - TP management. Having a stacking buff (like wrath or aetherflow) that is increased by paying a large amount of TP, these can then be expended to perform hard hitting attacks (or restore TP). The idea is that SAM would hit hard, but slow.