Ultimately it is about money and those with a long view know you can't make money if you do not exist. Since it is inevitable that the conference will be raided, planning to survive as a 2nd teir to the Big 10/SEC style of conference is the prudent thing. Hence a team with value enough contribute to the post inevitable raid should be considered before the Big 12 has locked up all the best options and are in a position to make the inevitable raid a dissolution.
It's already obvious that if the ACC loses Clemson, UNC, UVA, and FSU/Miami, that the conference will be in as bad a position as the current PAC-12, or worse. When that day comes a portion of the remaining teams of Miami/FSU, BC, Syracuse, Pitt, VT, Louisville, Wake Forest, Duke, NC State, and GT have to choose to stay together with the additions of schools like Memphis, SMU, Tulane, UAB, etc... or join a Big 12. If 2 or 4 of those remaining teams join the Big 12, then there is no hope of the ACC not dissolving or limping on as an AAC/Sun Belt level conference.