I do not believe this. I had seen it reported other places tonight before being here.
If Nolan wanted this Warner Bros would have allowed him with no hesitation to do this a LONG TIME AGO. So for it to be true it would mean he completely changed his mind.
Its is possible.... I guess. I think it would only undermine his explanation for his intentions behind The Dark Knight Rises
ending. But within the actual film its very vague. All we actually see is that Bruce is alive and Blake has discovered the Cave. We have no clear ideas of what happens after that. Bruce could resume being Batman and Blake could be his partner. I have no doubt that it was written to be open for multiple theories on what happens next.
Still, it would mean a total change for Nolan. Unless he is just a producer and sees his story complete. But is willing to let others add to it. Like Lucas has with Star Wars.