There's got to be wiggle room. I also noticed in the linked story that another "Avengers" movie is slated to be released in 2015. Might be Disney would want to evaluate whether or not its "Star Wars" movie would be in any competition with its "Avengers" movie.
A "Star Wars" movie and an "Avengers" movie in the same year. That could be a billion dollar year for Disney, easy. Maybe Donald Duck will finally have enough money to buy some pants.