Popularity will bring more people, but its not like a thousand future NFL'ers will decide to be MMA fighters instead of playing football. If this was the case, right now they would be trying to box instead of playing football, wouldnt they? Some folks just dont care for fighting, no matter how physically able they are. Combat sports gyms will also never, ever be as common as football/basketball programs (boxing gyms are hard to find, and have never been very common in most parts of the country) and a whole lot of parents (who are the biggest influences on sports for youngsters) are not going to care for thier kid getting hit/choked, again, if money were the driving force in sports participation (its not) Boxing would have alot more of the draw you seem to think MMA is going to have in the future.