Christopher Nolan finally opens up about the prospect of a 3rd Batman film in an interview with LA Times. He's shares his thoughts about his last movie and talks about what it will take to make a third one and the dilmma of the third-film curse. He does not go into any details about a plot because I don't think he has a solid idea for it yet, but here is what he says when asked about a third Batman film:
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.
As for the Joker the character was left open ended. It would be possible for the character to return. I can't imagine it myself because I couldn't see anyone else playing the character at this time. When Nolan was asked about if he anticipated The Jokers return to Gotham city to raise hell, he said:
No, really and in truth, I only deal with one film at a time. I find myself sort of protesting this issue a lot. 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's 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.
I totally see what he is saying there, but at the same time I totally saw that ending of the first Batman as a tease for a second film. He then goes on to say:
Then I got excited about seeing where that character would go. It was planned in advance, but it followed in that way. But we 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.
Hopefully Nolan finds another fantastic story to work with, because I would love to see another amazing Batman film. We may have to wait a few more years but I think it will happen.