I think a good analogy is boxing. For those of us old enough to remember, the sport was right there with Baseball and Football. Basketball and Hockey were a notch below.
Boxing still exist today obviously, but it is no where near the level it was 30-40 years ago. Somewhere along the line, some, not all of the would be boxers moved to different options. Why? because you don't have to get you head bashed in to make a lot of money. And, only a few boxers made money.
Could we be headed towards an era of only those without other options stick to football? I think it is very possible.