The BIG and the SEC ditch the NCAA. They form a new super conference by joining together and having one super conference. They add more top football teams/schools to the super conference to get to 40 total teams. They play only schools within that 40 team super conference. They govern themselves. They figure out how to deal with NIL so that schools are not paying players to commit.
They dominate college sports and media. They set up a national championship by having a playoff for the natty by taking the top 8 teams in the super conference with the best records to compete for the natty.
They set up the basketball and baseball natty, using the same model currently in effect except the only schools participating are the 40 schools in the super conference. None of the 40 schools will compete in any athletic contest outside of the super conference and no school not in the super conference will compete in any athletic contest with or against any super conference team.
They run the natty and get all the money. If other schools want to play for a natty or whatever, they can do whatever they wish, but none of the super conference teams will participate.
due to injuries (brain and other crippling situations such as knees), cost, loss of public supporters, colleges deciding to drop it (b/c of above), etc.