The major threat to football participation at the prep level is Moms who don't want their kids to play because of injuries. Especially in the middle and upper middle economic classes. Prep squad rosters now are much smaller than when I played many moons ago.
And more early retirements at the pro level when guys who've already made a ton of money bail out for the same reason. (Guessing strongly influenced by their wives.)
Link: Panthers LB Luke Kuechly, 28, says retiring from NFL is 'right thing to do'