Overload
As Steven Spielberg says, much like the western (which was the go-to genre until the late "˜60's), the superhero genre will fade away simply because the audiences will get tired of it. The western genre isn't the only example which can be given: the war movies, the swords and sandals epics, the historical films, and so on.
And it is easy to see why Steven Spielberg says that "“ adding the rumored and the unannounced superhero movies, in the following 5 years we will have about 10 superhero flicks per year. Which is a lot. How long can this last, in this rhythm? Not too long, we guess, until the audiences will want something else, something new or at least something different.
But is this the case? Not necessarily "“ check out the next page too!

