For the weekend as a whole, ESPN and CBS were up, NBC and FOX were down, and on aggregate ratings across the NFL were up about 3 percent from Week Three last year. So there’s no reason to believe that the national anthem controversy hurt the NFL in the ratings department.
Reading Something in the N.F.L. Ratings? You’re Probably Wrong. (The New York Times, 8/25/2017)
Across all live sports, though, it is likely that ratings will continue to drop. Viewers are continuing to abandon their cable packages, or refusing to sign up in the first place. And as more and more games become available, watching any single one loses importance. Games will continue to shift from network television to cable to internet streaming services, which are available to a smaller customer base.