Huh?
"Superhero movies" is not a genre. That's why the MCU has had such success. The movies they've made have been everything from Sci-Fi/War (Iron Man, Thor, Cap), Action/Comedy/Fantasy (Guardians of the Galaxy), Heist-Comedy (Ant-Man), Coming-of-age (Spider-Man: Homecoming), Team-ups (Avengers, Ultron, Civil War, Infinity War), Spy-Thriller/Cultural film (Black Panther), Mind-trip/Action (Doctor Strange, Ragnorok).
As long as the MCU keeps the genres different from film to film, while still feeling like it belongs, people aren't going to get bored of these movies anytime soon.