I have seen the decline of football in my well off suburban neighborhood. The local youth league used to field 13 teams in the most frequent weight class, now it has been pared down to four or five teams. Boys who like contact sports tend to turn to lacrosse.
One local coach thinks the challenge is steep. It is hard to obtain truly good coaches (in response to the concussion problem, there is lots instruction on tackling, some of it conflicting, including something calls Heads Up football, which seems to me to be just as much of a problem as it encourages a bigger player to engage in rag doll type tackling with heads bouncing on the field).
I appreciate this guy's comments because even with instruction, there is little chance I could be a competent youth football coach (basketball I played in high school, and I find it much easier to coach at the youth level - ditto for track and cross country, where all you really want is low pressure participation for the young kids).
There, too, is a push to make weight classes narrower in range for pee wee football to minimize injury, making it harder to field as many teams. And suburban parents are far more cautious than they used to be. My daughter's high school - state champions in XC and football 12 years ago, is still very competitive in XC, but is having trouble fielding enough numbers to make for a meaningfully competitive team. If youth leagues suffer (football is not easy to learn to play well), the sport will suffer at the more senior levels.
I don't think the fall-off is as steep in less well off environments. But one wonders whether football will go the way of boxing, although college football is today very popular in the south.
I am a football fan, largely because my grandfather was a pro football player and watching football makes me feel a connection to him. It took years off his life, however. He would have enjoyed watching my brother and me compete in NCAA Division 1, being a sprinter himself, and his somewhat abbreviated life from pro football prevented him from doing so. Notwithstanding, I am nowhere near as avid as a fan as I used to be, and would not spend the time or money to go to a NFL game now.