Sequel rule #1: Never write out major characters from the original without a good explanation.
Regardless of whether or not you liked her, Bastila was a key player in KOTOR 1. You can't just silently ignore her impact on the events leading up to and surely following the first game any more than you could ignore Revan's. Sequel rule #2 is to never crap on the original's ending, but that's a different story.
Personally, I would have preferred that they went with the LS ending from the first game and kept most of the characters, and given us some new enemies (I fought enough Sith Troopers and Dark Jedi on the Star Forge, giving me a different character isn't going to make that fun again). The formula worked. KOTOR is the only game I've ever played where I actually played the same levels over and over again just to hear the different character interactions. Soon, the game isn't just about the hacking and slashing or the lightsaber duels, it's about the story and those involved with it.
I don't think KOTOR would be half the game it is without its deep, well-written story and its endearing characters. I don't know anything about Obsidian, so I have no idea whether or not they'll be able to emulate that. I certainly hope so, otherwise we may be looking at a dry, repetitive sequel on par with Matrix 2 or Deus Ex: IW.
Anyway, there's always optimism. 100%.