I'm always amused when people suggest that because something is pop fluff it will be forgotten.
Let us remember that popular things are usually what gets remembered. We look at Shakespeare as high art today and forget that he was writing for a mass audience and was sure to make his work as scandalous as possible for the time.
Authurian legend and Greek epics were also the popular fiction of their respective historical eras.
Sherlock Holmes was popular fiction of it's day and here we are a century later and he's still remembered.
No matter what happens to comic books in our more digital future, it's almost a foregone conclusion that the likes of Superman and Batman will live on in some form in the popular imagination.