The release of the Sith Warrior class, (which was shown with the gameplay footage as a world premiere) should not be a surprise to anyone. I actually had been so expecting it that I had forgotten they hadn't announced jedi and sith as playable classes in their story driven MMO.
This brings the total to 4 announced classes. Bounty Hunter, Smuggler, Trooper and Sith Warrior. At the moment I assume Jedi will be up soon, and I imagine they re trying to come up with a way to differentiate them from Sith in not just story. After that, I'm starting to draw a blank. I don't think some traditional professions like medic (or a healer) will play out as well in this story driven MMO since it still seems more focused on the individuals story, as opposed to the party. I would say I could watch the movie for inspiration on guesses, but this game is Three thousand years before, so no go there.
This Sith have some nice hilts though. Don't know why they feel the need to steal others!