King James is locked with the Cavilers for another two years, with the option for a one year extension. I guess his willingness to continue playing with them will depend on how well they continue to surround him player that will help him win a title. If it's not happening, I don't see him pulling a Garnett and stick it out.
So he will either go to a team that has a good chance of winning a title or a team that has a bigger market.
I think we'll know a lot more after next year, but the Lakers and Knicks probably have the biggest markets, and if you look to the past for answers Wilt, Kareem and Shaq all gravitated to LA eventually.
Last I heard was he was rumored to be heading out to the Nets after they move to Brooklyn.