If ACC still has 2 of Clemson, FSU, Miami, or NC, I wouldn't be shocked to see no ACC defections. Or if FSU, Clemson, or NC are still around (Miami by itself doesn't have the pull unless they become a juggernaut again), still not sure if anybody from the ACC goes to the Big 12. Hope I am wrong.
The ACC teams love their network, love being in the ACC, and view the Big 12 as being beneath them. Unlike the Pac, the ACC added teams to withstand defections and would add more if anybody else leaves to stay at a minimum 16.