He won't leave Lyon at least for another two years, possibly three. He's only 19, and he would be foolish to go to a club where he'll be the fourth or fifth striker, when he can be a starter for the best team in France, get call ups to the NT, and play in the Champions League every year. The only way he'll improve is if he plays constantly.
Lyon won't sell him anytime soon either, because Benzema extended his contract until 2012. Aulas has made it clear that both Benzema and Hatem Ben Arfa are the future of the club. And as neither player want to leave...