I think your timeframe might be off in that it takes more years then you think but the informal part is spot on. The major problem is that with the new BIG/SEC deals coming does that change who could be added that wouldn't reduce the payouts for other schools? If we are talking 80mil per school what other schools outside of those two conferences could bring that in? Also one of the other things that I know you don't believe but I will keep saying is that the BIG will do everything possible to not expand and keep things the way they are. Will it work? Not sure but they will try.
But per school payout is not going to be the key question. For the SEC and Big it will be how many teams in a league are needed to keep it rolling. The short answer is maybe nobody short of ND increase per team payout, and most current BIG and SEC schools are way on the wrong side of the per team value equation and are being carried by a handful of huge names.
But what maximizes for the BIG and SEC is getting to X number of teams in a division. I think that is 45-60. But rather than expand and probably take on teams that lower per team payout, better to work out agreements with the other leagues for scheduling, playoff, etc.
Expansion doesn’t make sense for BIG and SEC (short of a couple options) but neither does EXCLUSION. Keep a big, 45-60 team division with national exposure and interest, maintain a big $ advantage over the other conferences and have no financial responsibility for them. The networks also do not want to see exclusion. The networks do not look at or give a crap about payout per school. That is meaningless to them. For them it is about marginal profit over alternative programming. CFB of any of the current P5 fit that bill, but if teams are relegated, that probably plummets the calue of that programming.
We may see some realignment, but I do t see major expansion in Big 10 or SEC. I see deals on playoff expansion that include the ACC, Big 12 and PAC.
People need to dump the per team payout as having any effect on who is part of an exclusive league. It effects conference expansion, but not who is in a “division.” An exclusive League with many current P5 teams relegated out of the club is not an advantage to the customer in this relationship, who are the networks.
Not to mention IF there were to be a 32 ish team league, this could be very valuable, but ultimately getting rights to that will be very expensive when it goes to market.