Not at all possible. The P-5 power today means it's get in or be relegated to the peanut gallery. The control the rankings, and the only post-season games that pay out 95% of the bowl money. It definitely looks like the NCAA has been forced to virtually cede much of its power to the P-5. With the P-5 moving to pseudo-paying its players and severely limiting OOC games to mostly other P-5 opponents, we've already moved to a de facto 2-division split between the half of I-A division teams in P-5 conferences and those on the outside looking in.
When UCF went from 1-AA to 1-A, there were fewer than 100 1-A schools. Now there are nearly 130, with nearly all non-P-5 programs losing millions a year. At UCF and USF, over 40% of operating costs are borne by students in outrageous student fees per credit hour. As SEC's UF, they wealthy students have to cover only 3% of athletic program costs. Most other of these 70 non-P-5 sports programs are also between a rock and a hard place. Remain mediocre and still lose revenue because of low revenue, or raise your revenue by pouring added millions into facilities, personnel, equipment, and marketing which balloons your costs, may still not be successful. Even if you enjoy success, P-5 conferences always hire away your winning coaches because were are their minor leagues develop P-5 future coaches. So if you grandfathered your way into a P-5 conference, like MSU, Washington St., or Vandy, you're set for life.