Christopher Nolan to make a 3rd Batman movie?

There has been talks of Christopher Nolan, the director of Batman Begins & The Dark Knight thinking of making a 3rd Batman movie. Christian Bale has also agreed to make another one if the director agrees to make another one. I read where Christopher Nolan and the actors has signed a contract for 3 Batman films. I was just wondering, I know The Dark Knight just came out, but when do you think a 3rd Batman movie would be in the making? Within a few years maybe? Thanks!