The P5s all leave their conferences (and shun the NCAA) to create their own league.
Ironically, there are 68 teams in the P5s + ND. There are 68 teams in the NCAA BB tourney.
So each team plays 6 games, respecting regional and historical rivalries. Then a committee seeds all 68 into a march madness type tourney. The rest of the season is that tourney.
Add in losers brackets and utilize the existing bowl games.