Problem is that would qualify as quite a BIG plot twist, and from most interviews, Obsidian has said there isn't going to be a major plot twist like there was in KOTOR.
It would also cause problems with the game because assuming your theory is correct, then Kreia would have BOTH Revan and Bastila's abilities and thus be one of, if not THE, most powerful Jedi in the game. And considering we meet up with her early in the game, it'd seem rather weird to have a level 1 PC hanging out with a level 30 (or whatever they have the max set at) Jedi.