I don't see any reason for him not to be in the second film or the sequel to the Incredible Hulk, if the film will be made. There was also an interview with Leterrier in which he gave a hint that this is just a beginning of a story, and that he hopes the Leader will be in the next one. We even saw the origin of the Leader. Why not have Norton for Hulk if the sequel ever happens? Too bad if they won't have a bigger budget, because of this one's disappointing numbers. I hope the extended edition, which is in this case inevitable, will higher the chances for the sequel.