Take a look at Captain Marvel. He was the most popular superhero in the 1940's and he even outsold Superman. He was also the first comic book superhero to see a film adaption. The entire Captain Marvel franchise was so popular that Elvis (who was a huge fan) actually took his hairstyle, manner of dress and overall look from Captain Marvel Jr. Now look at where Captain Marvel is today.
Is it possible that the same thing could happen to Superman?
What do you think it would take for that to actually happen?