Boxing is said to be one of the oldest sports. Hard for Americans to believe but in "The World", boxing is more famous than American Football. It's true.
Boxing is well known in every country execept India, China and Mongolia. American Football is only popular in USA and Canada. Soccer rules the entire world, its the undisputed king.
If boxing has been here for centuries, what makes you think it will just vanish in as short as 50 years? No way. I bet anything that Boxing outlives the NFL. People of the world have been exposed to the NFL but the sport is just not appealing to them. Boxing will always draw a crowd. Always no matter what.