...a majority (numerical) of NFL draft picks are lower rated and unheralded 3* coming out of HS and develop during their college years and become NFL talent, showing just how much talent transitions from HS to college each year.
So with all the "known" high-end talent (i.e. 5/4/ high 3* recruits) plus all the NR, 2*, 3* etc that will eventually develop, there will be more than sufficient talent to support more than just a power 2 or super conference because there simply aren't enough starting positions across just 25 or 30 teams to accomodate them. Due to this fact, you'll have the TCU type years where teams that "aren't supposed to be winning" will be winning still outside the designated P2 and create instability in its structure.
I will stick to my guns on this, there are more than enough really good football players to go around and compete even outside the P2, if they choose to try and make that happen.
You will also have loss of national audiences which will lower revenue if you only have a handful of regions that power football is really relevant. I see a lot of headwinds if they really push to try and create a compact power league.