I think the NCAA will still exist just like the NAIA does. Running Track and field and rowing competitions does not need a gigantic organization another cost savings.
I’ve said it on here before but I think the mainstream team sports where you have teammates working together on a floor/field will get pulled into this new “CFP” like organization: men’s football, basketball, baseball, and women’s basketball, softball, volleyball, soccer.
The more individual Olympic can remain with the NCAA, these generally don’t make money and would limit teams from competing against the best. The best golfer, swimmer, or runner could go to Harvard or UCSD but it’s unlikely that their mainstream team sports would be competitive enough to truly compete for a national championship. Examples are: Tennis, Golf, S&D, T&F, cross country, wrestling, and gymnastics.
The more regional sports with less participation would also need to stay in the NCAA for the wider field. Here are some examples along with how few currently compete in a P4 conference men’s soccer (30), rowing (30), LAX (15), ice hockey (10)…