OP made some interesting points

1)Saban retiring. Saban is the most adaptable and trend seeing coach in college football history. But he brings eyes to TV sets because of his emphasis on the defensive side of the ball. All this spread RPO up tempo offense that is "ref-assisted" (I see you Kyler Murray) brings in marginal fans particularly women and 12 year olds in adult bodies. These are of course the first fans to leave and go on to new things. The core college football fan loves what Bama represents- a strong running game and a strong emphasis on defense. Fortunately I do not think this will change even after Saban leaves.

2) Players sitting out Bowl games. It's bad but understandable when big name players sit out bowl games. It's going to cause both Bowls and the Networks to rethink how they market these games, But the key issue will be when big name players sit out Year 3 to "concentrate on the draft". We've had players like Jadaveon Clowney who mailed in their last year on campus. But after Joey Bosa this year we will no doubt see players sitting out their last season.

3) The AAF. I have no idea about the AAF. But I assume that they will adopt the same 3 year rule that the NCAA and NFL have worked out. Will players straight out of high school risk going to a new pro league for marginal salaries and injuring their undeveloped bodies? I'm sure they will. But once people see players have their careers ended at 18 or 19, most will opt for the development and care that you get at a major college.