With the Big Ten pulling a number of additional schools (Virginia, UNC, Duke, Georgia Tech, FSU and either Vandy or Miami) the Big Ten schools would be making insane money and the ACC would be dead in the water.
The loss of those ACC schools would have ESPN looking to drop the per team
payouts from $17 Million per school. That would have every school
looking for a way out.
The Big Ten payouts would likely dwarf other conferences. The Big 12's plan was to try to capture Florida State and Clemson to spike the conference's payouts, but with FSU out of the picture and Big Ten payouts off the chart, joining the dysfunctional Big 12 would not be at the top of any school's list.
The Big Ten's per team payouts would skyrocket causing the SEC and Pac-12 to again look hard at expansion.
The SEC would quickly scoop up North Carolina State and Virginia Tech to get access to those states. In an ideal world that would be all the SEC leaders would want to do. That kind of addition would help their per school payouts, but would not equate to Big Ten money. Keeping up with the Big Ten's money is important to the SEC, but regional play matters to SEC fans. It would be a tough balance to maintain.
Those schools are the easy adds. The tough debates in the SEC are Florida State, Clemson, and Georgia Tech. Those trio of schools allegedly were historically blocked by Florida, South Carolina, and Georgia working together. If FSU and Georgia Tech were off the board, it would be pretty likely that that alliance would collapse and that Clemson would likely find their way in at some point.
If Vanderbilt was lost, the SEC would also be in a tough position. With no private schools in the conference, the SEC would be subject to freedom of information requests. They would not tolerate that, so almost immediately a replacement private school would have to be added.
The SEC as a whole does not appear to be strongly in favor of adding Miami with it's Northeastern attitude, but in such a scenario it could make sense to add a private like Miami to restore their ability to avoid FOI requests and be perceived as a strong add.
Other candidates to replace Vandy as the token private would be Wake Forrest and former SEC member Tulane. While schools like LSU and Florida might balk at the addition of a better academic school from their own state, NC State would likely welcome the addition of another NC school. It is hard to see how the dynamic might unfold.
Tulane may have a lot of "tradition votes" to return. Or maybe not.
For now, we will say Virginia Tech and NC State only in if Vandy stays. Miami, Wake Forest, or Tulane in if they go. I think the SEC would sit at 16 for a year or so to regroup unless someone forced their hand.