Purely based on what i feel the classes still lack and suits their style, feel free to express ur own thoughts or look down/up on mine:
Warrior: Another power oriented elite with considerable duel power, likely gaining bonus from duel.
Guardian: I dont have a clue this class can do anything with its current elites already
Revenant: A very bursty stance
Ranger: Some extra interaction with its pet and potentially making it the main combat power instead of the ranger itself
Thief: An elite that focuses on a more sustained style of damage
Engineer: An elite that excels in healing and other form of support. Might have some interesting mechanic that gives teammates certain equipments to use
Mesmer: Focus on keeping the clones alive and benefiting from doing so rather than sacrificing them all the time
Necromancer: Pure ranged shroud that benefits from not taking damage
and last but not least,
Elementalist: Some even more complicated mechanic that no one will understand without four years of practice!