Agree to some level. Not sure I agree that they would put BYU in the top 1/3 of P5 teams if they truly broke off. BYU is certainly more attractive than a bottom feeder P5 school (think: Kansas, Rutgers, Oregon State etc) but if the group is so exclusive I don't see it.
Additionally, there will be long seasoned relationships that will drag some team in. Example: OU could drag in Ok State (no idea the relationship, but things like this will happen).
You are also neglecting the non-football aspects of this (religion, PR, liberal universities/students) that would keep us out.
BYU does get eye balls watching on TV, but I do think there is a cap. We draw consistent numbers from our base, but could we take it the next level. I think there is a reason we play games at 1030 PM ET, we can still draw viewers given our base but we are not a prime time game very often. We are not going to ever compete with the big time games (ex: Notre Dame/Clemson this season).
I hope you are right, but I don't see it.