I don't see Norton coming back unless he gets to direct the film and gets final cut -- which isn't going to happen under the Marvel bosses.
They've tried this character twice on the big screen ... I just don't think he works. Is there really some compelling area a sequel would go to that would expand the audience of the film?
I don't think the brooding, loner Bruce Banner/Hulk thing really works. It's too drab and dull.
The only route I could see it working as would be to make it more sexy/stylish ala Transformers with a Megan Fox type female lead and lots of city-destroying brightly lit action. And probably a younger actor playing Bruce Banner.
This worked for about 50 years in other media though...
I really liked what Norton and crew did with Hulk, and would like to see more. I never really read the Hulk in comic book form, but I'm sure there's areas they can get into. Be nice to see a bit more of a do-gooder Hulk prior to the Avengers movie.
I think part of the problem is that The Hulk has seldom been the completely feral, inarticulate animal that we keep seeing in the other-media adaptations. I don't necessarily want a Joe Fixit or the Banner-in-Hulk's-body situation that they had toward the end of Peter David's long run on the comic, but some way to make the Hulk more of an active participant in the story might be appreciated.
Though the two films made about the same amount of coin worldwide at the box office ("Hulk" earning $245.4 million compared to the $262.1 million earned globally by "The Incredible Hulk"), what seems to have given Hurd more hope that there will be a sequel is how strong the movie has performed on DVD/Blu-ray since it was released last week. IH will easily out-perform the Ang Lee film on home video, which is what both Marvel and Universal execs had hoped for.
With Hulk expected to appear in "The Avengers", this will probably add more fuel to a IH sequel. It is not known whether or not Norton will appear in "The Avengers", but as Hurd pointed out, he does have a multi-picture deal covering both "The Avengers" and any IH sequel(s).