I can't look it up right now because work blocks gaming related sites, but I think it's on the official website somewhere. Anyway, the gist of the matter is that they're aiming to add in extensive on the fly character customization specifically to avoid the hour-long search for healers (for example) that other MMOs have problems with. I don't know how it'll work, but it sounds like that's something they're trying to address from the very beginning. You should be able to go do things no matter what class mix you have. We still may end up having an enormous Jedi population, but it shouldn't matter too much if the class imbalance doesn't break the mechanics.