I mean, has he even come close to saying what type of genre he'd like to explore in the future? Or perhaps shed light on some ideas he had for a future project?
Knowing Nolan, I doubt he has said a single word to anyone. I'm sure any of his ideas are probably locked within a safe 10 miles beneath the surface of his home.
As far as I remember correctly, I read somwhere (an interview?), that Nolan has some ideas for the next film. But that's all, no more details. My memory fails sometimes, so a link to prove this would be great.
EDIT
Ok, I found it! It was interview with M. Caine and quoting his words:
“He’s got to go on, he’s got some other idea, and I’m in it! I’ve been in everything he’s done since he’s been in Hollywood. We’re each others’ good luck charms,”