where is this data? I can't find an official link on the National Federation of State High School Associations.
Most recent data they have is for 2014-2015 season with 1,085,182 participants. Nothing for 2016/2017.
2013-2014: 1,094,949 participants
Overall, football has been on a slight decline since 2008/2009, where they had 1,113,062 participants.
http://www.nfhs.org/ParticipationStatics/ParticipationStatics.aspx/
I wouldn't be so dramatic about football going anywhere. It's still #1 in terms of participants according to the data. I'd love to know historically how it has fluctuated. I would assume fluctuations are normal. Is 25,000 (if that's even accurate) completely out of the norm historically? I don't know.