The Los Angeles Times has posted the first part of its three-part interview with Batman Begins and The Dark Knight director Christopher Nolan in which he briefly addresses what will determine whether he’ll be back for a third film:
Well … let me think how to put this. There are two things to be said. One is the emphasis on story. Whats the story? Is there a story thats going to keep me emotionally invested for the couple of years that it will take to make another one? Thats the overriding question. On a more superficial level, I have to ask the question: How many good third movies in a franchise can people name? [Laughs.] At the same time, in taking on the second one, we had the challenge of trying to make a great second movie, and there haven’t been too many of those either. Its all about the story really. If the story is there, everything is possible. I hope that was a suitably slippery answer.
You can read the first part of the interview here.