At this point, it seems almost certain that John Williams will be returning to compose the soundtrack for Episode VII; He’s said he’s like to do it and director J.J. Abrams think he’ll return. Even longtime Abrams collaborator Michael Giacchino thinks so.
In an interview with Zap2it, the composer said:
“We’ve certainly talked about that, and I’m happy and willing to do it,” he confirms. “J.J. Abrams, who will be the director, seems excited about the idea. I have to say that J.J. is a much younger man than I, but I will try to keep up with him as much as I can!”
I’m not sure that “talked about that” infers that formal negotiations are currently in progress, but it does show that he hasn’t lost interest.