I don't know how reliable Batman on Film usually is for this kind of news, but, if it turns out to be true, I suspect that Nolan would be returning. I don't think WB would risk facing a negative reaction from fans if they announce that Nolan isn't returning. It may piss people off enough that they avoid Inception out of some anger towards him.
I think he will do Batman 3 and he's set up the third one in a great and wonderfull position. I'm sure he will find the potential storyline of Batman being viewed as a villan by people in Gotham, as something he just can't walk away from.
I would bet good money he will sign for the third one