You are leaving out the biggest part of this equation. What does TV want?
The guys putting up the money are going to want to have a say in what happens. If ratings stay strong and the new playoff system generates more ad money, I’m not sure much will change quickly.
The NCAA controls the TV deals for everything outside of football. I’m not sure the networks want to scrap their sweatheart basketball deals and rework them with some brand new entity. In that regard, I’m not sure they ever go away even without football.
I think a new entity to handle just football and conferences that are football only will be the way of the future but how far away will depend on the success of few years of this playoff model.