Three divisions: FCS, G5, P5

Lowest ranked team in G5 and P5 gets relegated to FCS and G5, respectively. For example, Cal or Colorado would have been relegated to the MWC last year for this season, and Hawaii would have been relegated to the Big Sky.

Highest ranked team in FCS and G5 get promoted to G5 and P5, respectively. For example, Fresno State would be in the PAC 12 this season and Eastern Washington would be in the MWC.

It would really get rid of almost every concern I have of lack of fairness in bowl access, playoff access, revenue sharing, etc. There's also probably more money in it this way - think of the people that would have actually watched Colorado and Cal at the end of last season - but the concentration of money in the current conferences would be threatened so it would never happen.