"Without getting into specifics, the key thing that makes the third film a great possibility for us is that we want to finish our story. And in viewing it as the finishing of a story rather than infinitely blowing up the balloon and expanding the story... I'm very excited about the end of the film, the conclusion, and what weve done with the characters. My brother has come up with some pretty exciting stuff. Unlike the comics, these things dont go on forever in film and viewing it as a story with an end is useful. Viewing it as an ending, that sets you very much on the right track about the appropriate conclusion and the essence of what tale we're telling. --Chris Nolan
http://herocomplex.latimes.com/2010...ht-with-superman-we-have-a-fantastic-story-1/
"It's really all about finishing Batman and Bruce Wayne's story". --Christopher Nolan, January 2012 issue of Empire