In a interview with Parks and Resorts Chairman, Tom Staggs. Reuter's asked the question, What about a Marvel attraction.
Here is what Tom said ..
"We were hard at work on attractions using Marvel characters previously, and that work has only intensified given (the film's) great success. The Avengers has sold more than 1.3 billion worth of tickets around the world. Executives and Imagineers are still working out how to bring characters like The Hulk, Iron Man, and Captain America to the parks. The setting has to be right, the story has to be right, and that takes a fair amount of time"
Now keep in mind that due to certain legal issues, Disney cannot create or open a Marvel Attraction in Orlando without making a deal with Universal first. So the placement would be California and its International parks.
My personal guess is that you can expect The Avengers and Harry Potter to battle it our for theme park attraction supremacy in California come 2015.