Superheroes could still be around for long but by then they would be very drastically different just as they were going through before. Only this time this would involve both the death of the superhero craze and the shrinking of its fanbase. I think with anime we’re seeing a similar decline.
Anime and the like used to appeal to the masses but due to a declining, xenophobic nationwide population and poor pay rates there’s a possibility that they’d decline. The likes of Hayao Miyazaki, Ken Akamatsu and Hideaki Anno have been sounding the alarms before.
Akamatsu even talked about the Japanese comics industry adopting some of the vices that the American comics industry is prone to like work for hire cartoonists working on tired, old franchises.
I think this is already happening to an alarming extent especially with stories and franchises like Crayon Shin Chan, Doraemon, QTaro, Evangelion, Fist of the North Star, Gundam, Black Jack and Astro Boy where you have stories that are increasingly written by someone other than the original authors.
Then you add in suspiciously repetitive, interchangeable plots and characters. Those were there before but not to the same blatant extent like where anime is going these days. Superheroes are no stranger to this.
What would rock the superhero genre is what happens when the genre dies, where do superheroes go to next? Placing superheroes in non-superhero genres isn’t anything new, this was building itself up a lot in a number of stories which were sometimes apocryphal.
If the genre dies, superheroes would have to move to other genres for survival. I can see The Flash moving to crime fiction as a good example of where the trend is heading. This change will spell the death of superheroes as a genre whether if we like it or not.