Phase 2 of the Marvel Cinematic Universe has done a really great job of building on itself, not only maintaining narrative momentum, but actually increasing it. All the movies have had seismic impact on the world - Tony Stark stops being Iron Man, Loki takes over Asgard, SHIELD is destroyed and another Infinity Stone is introduced - and feel individually important to wherever things are going. Ant-Man just doesn't have that same feeling of being an important must-see. The real problem is the best thing that has happened to the franchise; Civil War. In turning Cap 3 into some version of the conflict around the Superhuman Registration Act, the movie has successfully overtaken Batman V Superman in terms of anticipation, but it renders Ant-Man a distinctly less important prospect. The hype around far off movies (say, learning about Avengers before Guardians) hasn't hurt films in the past, but the disparity between the hype of the films could be an issue. After fighting Ultron and no doubt seeing the group put under massive strain, to take a sojourn out to San Francisco just feels like an excuse to hold out on more fun. If it doesn't feel essential to the Marvel brand, then it'll be hard to get audiences buying tickets.
