Hey, grandchildren, do you still follow that cape man you liked so much? That... Batmin character? Oh, good, because Christopher Nolan has finally spoken on if he's doing a third Batmin movie! His answer: maybe. More specifically:
Well ... let me think how to put this. There are two things to be said. One is the emphasis on story. What’s the story? Is there a story that’s going to keep me emotionally invested for the couple of years that it will take to make another one? That’s 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. It’s all about the story really. If the story is there, everything is possible. I hope that was a suitably slippery answer.
Maybe he's right. You can't always maintain the kind of third-chapter quality of an Austin Powers in Goldmember.
You can read the full interview here, thanks to illfigure.