Changing the postseason format wouldn’t change anything.
Every P5 team has the same access. Go undefeated you’re in the playoff (probably). Yet only about 15-20 schools truly recruit at a level where you can compete. Expanding the playoff to include the Sun Belt champ would not have recruits spurn Alabama for Troy.
Reducing scholarships wouldn’t solve the problem but it would actually get more 4 star kids to the bottom P5 or upper G5