There are literally $100's of millions that separate/will separate the conferences and the percentage of the money that ended up in facilities + the future money invested in coaching will be lasting differentiators. Add in the massive fan bases and donor pools the legacy P5 schools have and it adds up to a structural gap between the two groups.

Those disadvantages won't help but the biggest impediment to a long sustained ascension is that the biggest conferences will continue to poach the most successful coaches from the Sun Belt. Unless you have an institutional coach willing to stay for less money (LaVell, Whittingham, Bill Snyder, Patterson, etc.) or you continue to hit home run hire after home run hire (Boise St.) it is difficult to move up the college football ladder.