You're actually claiming that the number of high schools without football "is not rising." Really?High Schools know that their communities demand it. Very few don't have football teams and that number is not rising.
So those articles about schools dropping their teams are fake news?
Whitney Young high school in Chicago (where I used to be a volunteer coach in something other than football) actually fielded a team this year?
Centennial high school, just up the road from me in today in Maryland also fielded a team this year?
Wow, fake news really is everywhere.
The number of kids playing high school football is decreasing by 2 - 3% per year while the total number of kids participating in all sports is increasing, and total population of the US is also growing by about 1% per year.
Yes, more kids play football than any other sport, but that's not all on the "popularity of the sport." A lot of that is on the size of the roster as compared to the size of the roster on other sports. More high school male athletes play other sports than play football, and the numbers are getting more skewed each year.