The B1G trumps everything (for everyone but Texas and ND). Mizzou would jump in a second. Vanderbilt might as well.
The key to expansion are Virginia and NC. If both go to the SEC then the SEC will have more AAU members that the ACC. Both the SEC and B1G have to be looking there for expansion (and Virginia is in the south btw). I think the B1G goes for Uva and Unc (or duke) or Missouri or BC or Vanderbilt. The options for the SEC are limited to Virginia, NC and OK (I suppose Kansas has an outside shot). I'm not sure what the sec does if the B1G poaches Vanderbilt and Mizzou.
It goes without saying anyone would take Texas or ND. The ACC might give Texas a sweetheart deal too. The others won't.