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.
That third franchise movie question is a good one. X-Men, Superman, Spider-Man, Jaws, Pirates of the Caribbean, Shrek, Jurassic Park, Star Trek, The Terminator, and The Matrix all come to mind as franchises with lousy third movies. Rocky 3 was a little ridiculous at least, and it could just be nostalgia (at the time, I was pretty sure Mr. T. was the coolest guy who ever lived) keeping it off that list. But Indiana Jones, Star Wars, and the Lord of the Rings (if you don't count that as one 9+ hour movie, which it kinda was) all had solid third outings.
Anyway, I completely understand Nolan's hesitance, I just hope his caution leads them to wait for the right story, rather than leading the studio to pick anther director and rush out a lousy third movie (which, sadly, I would still end up seeing on opening night, because I'm dumb like that... but you know you would too, so shut up).