I can think of a lot of overlapping reasons right off the bat, reasons that have a lot to do with why I don't watch much NFL anymore.
1) Politics - and I'm not just talking about Colin K, either. The NFL created the soil that sprouted anthem protests. Colin is an EFFECT of the NFL not managing its own house, not a cause. Think about it for a moment: the whole Michael Sam fiasco from start to finish, Bob Costas using what was supposed to be a memorial during the broadcast to work in his liberal political opposition to guns, writers who have taken it upon themselves to not use the name Washington Redskins (Goodell should have told any writer doing this that their credentials were revoked, and I'm sure if Tom Brady had been a writer he would have), and the NFL on one hand permitting the Rams to take the field with the 'hands up' (which was a total lie) gesture but telling Dallas they CANNOT honor the police officers murdered here last July 7 because they don't want to be involved in politics - they apparently don't want to be involved in NON-LIBERAL politics. (Oh and btw - the NFL needs to hire BLM to do their security if this is their position).
When I watch sports it is to ESCAPE from the politics at work, politics at school, politics at home - I don't need the NFL force feeding me their own version of morality, particularly in light of....
2) Concussion - this is a LONG-TERM problem for the NFL after how they handled it.
I will confess having serious misgivings myself watching football at all - yes, including Alabama. Concussion might explain Colin K's sudden transformation from mediocre NFL QB into mediocre spokesman for Hate America First
3) Mediocre division winners due to the four-team divisions
We have had 2 or 3 instances in the past decade of teams with records of 8-8 or EVEN WORSE hosting HOME playoff games against teams with much better records. Why? Four-team divisions. They literally reward mediocrity based upon geographical accidents. There is LITERALLY no reason to watch a regular season NFL game, especially if you wind up with a very good 12-4 team that has the misfortune of being in a really tough division and stays home while a 7-9 team goes to the playoffs. Now before you bring it up - yes, it happened in the old set-up in 1985, when the 11-5 Broncos stayed home while the 8-8 Browns made the playoffs. But that happened ONCE....not several times and teams did not have free agency like nowadays - so one could easily argue the Broncos got even with the Browns by eliminating them in 3 of the next 4 AFC title games.
Not now. We get a bunch of 9-7 contenders every single year because of the set-up.
4) Fantasy football
Who the hell cares? Nothing personal if you're into that, but it can't be that exclusive or even remotely fun. One particular year I had three friends in three different groups who all 'won the Super Bowl.' How is this even possible?
And btw - I played 'fantasy football' in 1983 in Germany with several guys...but we were actually more concerned with who won than 'how my fantasy player did.' Our version may predate what's here, but from what I've seen (save the defense) it isn't that much different.
It's boring as crap. Like I said - I was in the NINTH GRADE when that appealed to me.
5) College football is now on as often as the NFL
I think a lot of folks get footballed out on Saturday and rest Sunday. When it can literally make the difference in whether you make the playoffs or not based on a game OPENING WEEK, you pay attention.
Gray is right in that what's going to happen is college football is going to see these great ratings and decide "hey, if we put 2-4 more teams in the playoff" and that's going to kill them, too.
Btw - if the Trump-Clinton race is to blame for the lower ratings (one of the most absurd proposals I've ever heard) then shouldn't the NFL's foray into politics be BOOSTING their own ratings rather than lowering them?