Actually, Bale joked awhile back about how Nolan only has a contract to do one film at a time whereas Bale was locked in to do 3 Batman movies no matter what. So even if Nolan left after Begins, Bale would have been involved in the obvious sequel without Nolan. If I remember right, Oldman said he was locked into 3 movies as well.
Yeah, I knew that. Sure, Bale would have HAD to make the next 2 sequels even if Nolan left but he would have begrudgingly. If Nolan was to come back, which I think its safe to say he will not, Bale would also...if asked.