It's fair to say that KoTOR 2 won't be as deep story wise as PS:T simply because as somebody already pointed out (Forgive me forgetting names I'm new here), the dialogue will be recorded and trying to have audio lines for all the dialogue in a game like PS:T would not only be hugely time consuming but it would require a hell of a lot of storage space.
However even from the relatively scant information in the scanned articles it looks like KoTOR 2 is going to be more complex and closer to a hardcore RPG than the original. It's going to be a game with Prestige Classes, whole Parties than can gain\lose alignment points; closer interaction between Skills and features like Weapon\Item Modification. All of these things add up to a game that's looking to be much deeper than KoTOR and if it can sell (Which seems likely if only on brand name alone) it should pave the way for more "Hardcore" yet "Mainstream" RPGs. If it takes a Star Wars franchise for it to work that's fine in my book.
Jaesun, I remember hearing one of the Raven Developers (Jedi Outcast, Jedi Academy) talk about Lucasarts and how they were generally fairly open to story development even to the extend of including it within the Expanded Universe. Remember Lucasarts made an expansion pack (Mysteries Of The Sith) around a character (Mara Jade) who first appeared in a book, and then later had that charcter marry Luke Skywalker in another series of books. I think they'd be open to letting Obsidian take the story where they wanted, within reasonable limits of course.