Right now, Djokovic, Del Potro, or Murray could all conceivably be number one after RG, depending on how well any of them do. Most likely, is Murray right now at number 2 after RG, coming into Wimbledon.
I'm not too worried about Federer, because none of his main rivals did anything at the start of the year. We are on clay now, and Roger is the reigning clay champion.
Unfortunately not for very much longer Sean. Nadal will be reclaiming that title, and he's looking every bit an almost sure bet for that.