Pro football is currently the most popular sport in the US. However, it may have reached its peak of popularity.
Because of the inherent physical dangers of the sport, the NFL has recently changed many of its rules with regard to contact. As a result of these rules (which are subjectively enforced), the quality of the sport is likely to decline in the future. Also, with more information about the risks of playing the sport, less parents will allow their children to play football. This may lead to a smaller population of superior athletes who play the sport in the future.