When the Big 12 dies, it’s down to four conferences, which makes it nice for playoffs.
Basically the four remaining conferences will become mega-conferences, or for lack of a better word, regions. You’ll have the Southeast Region (SEC), the Atlantic Region (ACC), the Central Region (Big Ten) and the West Region (Pac-12). Each will have 20+ teams arranged into several divisions, with a Regional Semi-Final and Final.
Right there essentially is a 16-team playoff.
Interesting speculation, but unconvincing. If the Big 12 is doomed, then they certainly were deceived by the TV networks, which expressed a very clear opinion that the Big 12 should not expand.
The Big 5 conferences together have only 65 teams. Expanding all the way to 100 teams would dilute the Big 5 incredibly. Contrarily, smaller conferences like the MAC and SWAC have their reasons for existing, but teams like Central Michigan, Southern Miss and Charlotte would never and should never be in conferences with Michigan State, Ole Miss and Florida State. You’d never get away with rigidly excluding all teams outside of a Big 4. And being overly regional would kill interest in cross-region games. People WANT to see Stanford play Notre Dame. And are you suggesting Florida and Florida State or Georgia and Georgia Tech or Clemson and South Carolina be in separate regions, or that the ACC and SEC will realign?
If you have Navy & Air Force you should probably have Army in their as well. Why not have all 3 service academies? They’re not going to run out of money.
I’d also look at New Mexico & Wyoming. Both are state “anchor schools” with at least a local if not regional following (and New Mexico would beef up the Basketball portion of the conference too). With basketball in the back of my head I’d probably think about U Mass as well especially with the service academies involved.
New Mexico St, Colorado St & Utah St also attract a following.