Droid commander for Republic, Dathomir Force Witch/Warlock for Imperial.
Mirrored multi-pet/companion classes where one is all Droids and techy abilities and the other is all nasty beasty and renegade force user abilties.
Republic Game Hunters vs Imperial Slavers might work.
Teras Kasi or other non-force melee master could fit.
I'd also like to see future classes whose Adv. Class options have 2 Healing/Tank trees and only 1 DPS. Not sure if that could be done without overpowering them over the current tanks and healers, or conversely making them feel underpowered due to spending more talents to end up the same.
Droids as a class is probably the only very well defined archetype established in the movies that we don't already have as a playable route. Much like non-humanoid aliens though, I doubt we ever see them as anything more than companions.
