We’ve never attempted to save anything for a sequel or set up anything for a sequel. That seems improbable to some people because, particularly with "Batman Begins," the film ended with a particular hook [with Jim Gordon showing Batman a Joker playing card announcing the arrival of a new villain in town]. But for me that was just about the excitement of people leaving the theater with the sense that now we have the character up and running. I wanted people to walk away with that sense in their head. You know, that he’s become the Batman in the movie. That’s why we had the title come up at the end, because it was "Batman Begins," and it was all very specific to that.Nolan also denied that The Dark Knight wasn't intended to be complete in and of itself:
[W]e tried our hardest to really do everything in this movie that we would want to see the Joker do and to get that in the fabric of the story as much as possible. We wanted the Joker’s final taunt to Batman to be that they are locked in an ongoing struggle because of Batman’s rules. There’s a paradox there. Batman won’t kill. And the Joker is not interested in completely defeating Batman because he’s fascinated by him and he enjoys sparring with him. It’s trapped both of them. That was really the meaning of it. Of course what happened is Heath created the most extraordinary character that you would love to see 10 movies about. That’s the bittersweet thing. It was incredible characterization. It is a bittersweet thing for all of us.And so, what are the chances of Nolan returning for a third visit to Gotham City?
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.If he does return, one of the actors from The Dark Knight wants to come with him... even though it would require a small amount of suspension of disbelief. Maggie Gyllenhaal has expressed interest in playing Catwoman in a third Batman movie, although she admits, "it seems unlikely at this point, right?" Christopher Nolan on 'Dark Knight' and its box-office billion: 'It's mystifying to me' [Hero Complex]