It's not a Trump issue, but Trump has brought it to the foreground. I would expect that he will amplify the effect in both directions.
For me the interesting thing is watching the free market at work. Obviously the revenues went down significantly last year in pro football as a result of it, and the initial response was for the owners to quietly discourage it and hope it goes away. It didn't, and with Trump publicizing the issue, the effect should increase dramatically.
One plausible path that we could go from here is to see dramatically more players doing this, and some fans doing it as well, followed by and even more dramatic drop in attendance and viewership, and a huge decrease in NFL revenues. Since many of the costs of an NFL franchise are fixed, that in turn would likely lead to a huge drop in the size of player contracts, at which point the player's union might discourage it's members from doing this, but it might be too late, and revenues might never recover. Could this effectively kill pro football? I don't think it can end it, but it can certainly dramatically affect the economics, and could reduce the size of player contracts back to 1980's levels. It would also reduce the size of coaching contracts, obviously, and that might help bring back some sanity to coaching contracts at the college level.
“We have two ears and one mouth so that we can listen twice as much as we speak.” ― Epictetus