This is a slippery slope for me as I DO NOT want to see the Op leader/guild being FORCE to take a crtain advance class., saying that i don't mind them having an encounter that require a certain role e.g. a RDPS/MDPS; where this is already being use in NM EC with the exploding add's at the tank.
Also, I like to see some kind of legendary drop now., perhaps a drop from the final boss in a 8-10 bosses op
That's the balancing act that bioware needs to be aware of, but as the game is today I don't foresee any problems really. We only have 1 resource pool to "fight against", and not HP, Stamina and Mana which abilites can tie in to.
What could be done with regards to utilizing class abilities rather than the current focus on mdps/rdps, could be something like a 3 second interrupt cyclus, 4 second heal cleans cyclus, stealth mechanics forcing either stealth scan or knockbacks to "get out of stealth", class specific solo encounters - think like a mind trap which presents the trapped player with an enemy specific to their AC - or even the tree they have the most points in (to work with classes that have both heal/tank and dps in an AC).
They have to be REALLY careful about designing encounters that need 1 specific tank type like Shadow w. resilience, or mechanics relying on a Sentinel w. speedbuff or Gunslinger with its shield. It's fine that those make an encounter marginally easier, but the fight shouldn't be MUCH harder without them..