It's funny, because in the hierarchy created by the last round of this nonsense the CUSA was above the Sun Belt in the pecking order. But then two Sun Belt schools have one good season and in this moment of brain-dead blind panic the balance of power shifts their way.
I could see the Sunbelt grabbing 2 of the east division teams from c-usa. They clearly are working to become more compact geographically so this is a great opportunity.
Anyway, for funsies let's do three flavors of how this could play out. I'm going to assume you're correct that the MWC (and MAC) will realize the value of what they have and not be in play for any of this.
Option 1 - "Conference commissioners going full steam ahead in an insanely short-term thinking clout chase" aka dumb cynical option (most likely)
The AAC adds Louisiana Lafayette, Coastal Carolina, and Georgia State. Sam Houston State, Kennesaw State, and Jacksonville State move up from FCS to fill out the Sun Belt.
Option 2 - "The biggest schools wake up to the fact that this whole circus is just resume building for the conference commissioners, and is occurring for the benefit of everyone but them" aka the smart cynical option (less likely)
SMU, Memphis, Tulane, South Florida, East Carolina, Rice, UAB, UTSA, Georgia State, and Southern Miss leave their respective leagues and form their own new 10-team league of real football programs plus a couple of big growing market prospects in UTSA and GSU. Good programs, good stadia, big cities, in a defined geographic area, no useless mouths to feed, and collectively within the metro area of the lion's share of the country's best recruiting talent. All of them better off together than stringing together permutations of arriviste directional nowhere schools.
Check it out:
Then the Sun Belt picks one of FAU and FIU from the rump CUSA to replace GSU and add a Florida presence.
The now-shattered remnants (Tulsa, Temple, UTEP, North Texas, Louisiana Tech, Middle Tennessee, Western Kentucky, Old Dominion, Charlotte, Marshall, the other one of FIU/FAU) have no choice but to band together, and add UConn as a football only member to really complete the Ship Of Lost Souls Conference.
Option 3 - "The whole non-Power Five comes to the collective realization that they have far more to gain from cooperation than from competing against each other in this endless rat race" aka the fun, good for the sport outcome (never in a million years)
The AAC, CUSA, Sun Belt, and remaining non-ND independents (37 schools total) join forces to create four new 9-team leagues, playing a full round-robin schedule to crown a regular season champion in each league. Then during the usual doldrums of the week before the big rivalry Saturday, they pair off and play 1v1, 2v2, 3v3 etc matchups, with the two winners of the 1v1 matchups meeting in an overall championship game in the Superdome in New Orleans on conference championship weekend.
And each league gets one of Monday-Thursday for its own game of the week. All of this to create maximum value for a TV package, and something sustainable to grow.
The leagues as follows
Atlantic League - Army*, Navy, UConn, Temple, Old Dominion, Liberty, East Carolina, Coastal Carolina, Charlotte
(*UMass only gets a spot if Army wants to remain independent. The scheduling structure is important, no more than 9, sorry UMass)
Red River League - New Mexico State, UTEP, UTSA, Texas State, SMU, North Texas, Tulsa, Louisiana Tech, Louisiana-Monroe
Smoky Mountain League - Memphis, Arkansas State, Middle Tennessee, UAB, App State, Georgia State, Georgia Southern, Western Kentucky, Marshall
Gulf Coast League - Rice, Louisiana-Lafayette, Tulane, Southern Miss, South Alabama, Troy, South Florida, FAU, FIU
Look at this absolute beauty: