I don't think either X3 or Break Up will seriously impact DVC. You're really talking about movies with 3 different target audiences, a suspense thriller vs comicbook action vs romantic comedy. As far as target audience is concerned DVC is basically running uncontested until deep into the normal falloff cycle of movie revenues.
But in the summertime the big audience is teens and college students who are out of school without much to do. They will all be attracted to each of these films. The question is what will they be going to see when given the choice between X3, The Break Up or DVC?