Update - 4/30/13: During a Berlin press conference for Star Trek: Into Darkness, J.J. Abrams says,"...Again, for Star Wars it is very early days to know but I believe that going forward John Williams will be doing that film, because apparently he was there long before I was." (Transcipt via InsideMovies.EW.com)



During a recent concert, conductor John Williams thought back on the creation of the Star Wars soundtrack, which no one thought would last, let alone, span six films; he then said;"... I need to make sure I'm still ready to go in a few years for what I hope would be continued work with George..."
It has been mentioned that composer Michael Giacchino has worked on all of J.J. Abrams' feature directorial outings, but, it is tough for me to imagine a Star Wars film without John Williams' familiar themes.
Source: MovieWeb.com

Update: During a post concert q&a in Switzerland, longtime Abrams composer Michael Giacchino says if it were up to him, Williams would compose the score for the new Star Wars film. "He has been a great inspiration to me over the years," he continued. "He has been a great teacher to me and good friend and I would love nothing more than to hear more of his music from that universe."
(Source: UK Movies Yahoo)