That's true. You have people saying that these superhero movies are just a passing fad that are going to fade away anytime now and some of the most prolific of these people are the same people that go on and on about how they are destroying the industry. If it's a fad that's going to fade anytime now, they shouldn't be all that worried about it. If it's taking over the industry, it's not a passing fad.
What has really happened is that they have a new technology. Relatively speaking, CGI is a new technology, especially at it's current developmental level. It has allowed movies to visually show things and make them look believable that was not possible before or to do it far more easily.
It is currently changing the nature of movies in much the same way that "talkies" killed the silent style of film-making along with some of the unique qualities of the silent film. It is the same way that color destroyed the black and white movie with many of the artistic qualities that could be captured better and maybe only captured at all in black and white. I might as well say video killed the radio star.
People are flocking to it because it's something new and fascinating. It may fade some but I don't see too many silent movies being done anymore or too many in black and white. Right now, the superhero movie is dominating because it offers one of the best exploitations of this technology. It may fade some but I don't see it going away unless other genre movies find a way to use it too without being action movies.