Bob Iger:
"The Avengers isn't just a film. It's a franchise from our perspective. Obviously, it was helped a lot by the success of the 'Iron Man' movies and of 'Thor' and 'Captain America'. From 'The Avengers' we get a chance to make 'Thor 2' and 'Captain America 2' and 'Iron Man 3' and hopefully another 'Avengers' movie. So this one film that is immensely successful... is going to get a number of other films and franchises...We have an ability to leverage what was a very fun film done by a great group of filmmakers into something much bigger for the company," he continues, "and the effect will be prolonged and that's very, very exciting for us."
This isn't to say there won't be a Hulk 2 (3?), but I doubt we'll see it before Avengers 2. It seems like they have things planned out for the next few years.