Football only became the most popular sport in the mid 80's to act like it can NEVER lose popualrity is foolish and short sighted
It will take a decade or so but it will drop becaus of how dangeorus we know the sport now so less and less kids will play,it will go the way of boxing where you still will have poor people playing it and it wont go away but enough great athletes will go to other sports that it will be severly watered down
Fantasy sports and gambling alone will keep the NFL the premier league for as long as i`ll be alive.
NFL is just bettter suited for American culture, face it. There are only 16 games, so the fan only has to watch once a week. It is best suited for advertisters as there are much more breaks in the game and the history of the game has a hold of the fans in a deep way.
Add to that the spectacle of the Super Bowl, it's just delusional to think the NFL will ever have a "downfall". I never said it couldn't lose popularity though. It can lose popularity by 15% and still be crushing other sports leagues.
And if you want to bring up danger, boxing, race car driving and UFC are plenty dangerous. I get the idea of parents not letting their kids play the game though, I can see it losing some popularity due to that.
Also, I can't see anything overcoming the sport. I think MLB, NHL and NBA are all tapped out at this point, I don't think they'll get bigger than they are, just can't see it happen.