The Thursday night games were just another avenue for ratings and additional revenues but what you have is just too much NFL football.
When I was growing up in the 1960’s it Sunday only, and for the most part they were afternoon games, not much night football. Then Monday night football came and it exploded, but still you had only Sunday's and the Monday game.
Now you just about 24/7 NFL of some sort from cable to apps for your phone. So I am not surprised that ratings may start trending down, the National Anthem controversy just adds to this.
I have predicted for several years that the NFL will eventually get to the point where it will have at least one game scheduled in every weekday prime time slot -- except Friday night, perhaps. We'll have Monday Night Football, Tuesday Night Football, etc. Even if their ratings go down, their revenue potential increases dramatically if they never again schedule two games to be played simultaneously. Spreading out 16 games in a typical week into 16 different time slots has tremendous revenue potential, when you think about it. In fact, it's so obvious that I can't believe they haven't done it already.