Jon Favreau points to the difficulty of the Super-Superhero Movie:
Still, though Favreau has passed the directorial reins on to Shane Black, he reiterated that Iron Man 3 could be hamstrung by Marvel's insistence on pushing Tony Stark into duty alongside its other heroes next summer for The Avengers. "I guess in comics you can say that it's an individual storyline and you can break it off into a group. But in movies, it's hard not to take into consideration what just happened," noted Favreau. "What are you gonna say? '[The other superheroes] all just lost their cell phones and you can't get help?' So it's going to take a lot of ingenuity to make it make sense to a mainstream film audience as well as a comic book audience."
I think that's most interesting aspect of Marvel's strategy--Can you create a universe, and a sense of inter-connectivity, in movies? The sheer expense prohibits doing it to the comic book degree. But is there a movie version? Are there any precedents? I don't know, as I'm not much of film historian.
It will also be interesting to see what DC does. Their Superman seems in limbo, they have no Wonder Woman, and their Green Lantern is just getting started.