I think the Big 12 dissolves (various reasons, just ask me) whenever the P5 becomes the P4. I also think the ACC will become a major (the strongest?) player in the P4 by shedding 1-2 of it's NC schools (Wake and/or NCST) and adding ND, UConn and Cincy to reach 16.
Unless it is something like the situation with Temple fb in the old BE; and the time before they got the invite to return for all-sports right before the conference basically disintegrated. While politics and pettiness were involved, Temple did little at the time to improve their situation prior to the ax falling. This differs from situations such as UMass' fb-only contract with the MAC or what the future holds for partial memberships contracted with the SBC. There's a big difference between not renewing an agreement, and a scenario where some school would be booted out as an all-sports member because of the perceived failure to deliver or the conference sees itself having too much saturation due to the number of schools in a particular geographic market.
Using the term 'shed' implies a conference action against their own, in terms of the referencing of Wake Forest and NC State, ACC charter members. Forced departures will not happen with either of those two. Both have strong alliances within the ACC. Wake Forest would be the last school that would want to leave the ACC. Voluntarily leaving for a better situation as Maryland thought---yes; but such, initially, may only be available to a handful or so of ACC schools at maximum if new circumstances allowed. There is alleged SEC interest in NCSU, particularly if UNC is off the table as a future option. Thus, NCSU may have appeal for elsewhere (namely the SEC) among the power 5; for Wake Forest, that's not there. Now, if the ACC helped facilitate, for example, a NCSU transition to the SEC in the context of a more comprehensive deal, then I suppose one could say they sort of shed somebody for what may be perceived as the greater good. But high profile departures seldom appear pleasant for the former host, and the ACC has shown itself to be highly spiteful with the Maryland departure.
If the ACC is able to pressure anything, maybe they should start with pushing to get a full commitment from Notre Dame. But ND has their terms with the ACC inked solidly. The ACC are the ones left 'hoping' with this deal. Never sign a contract whereby one party is left 'hoping', and the other is not.
There may be a future point whereby all major conferences are influenced or forced to drop or trade off members. This would be driven by broadcasting networks and marketing. But do we really want to see the climate for that to happen? It's forcing expansion already, but how long before they turn to deletions within a conference to make room to be more powerful and lucrative? Talking about really injecting instability and paranoia.......
Right now, the B1G, SEC, and PAC12, are the three conferences not apt to lose anybody. All of them will eventually add a couple or so members each and not lose anybody. The B12 and the ACC could, and probably will, lose members to two or all of the other three power conferences. The current GoRs' may certainly postpone it, but ultimately, not stop movement.
I believe the ACC and the B12 survive the next round of expansion. However, both will have significant change. The ACC can replace two to four loses and still be functionally respected but diminished in the perception of power. The B12, by comparison, is more vulnerable with any new loses. Even now, they don't see adding anyone brings value. If Texas and/or Oklahoma go, probably taking one or two with them, the B12 is devastated as a power 5 type. Even Kansas or Oklahoma State leaving, would hurt badly. The remnants of the B12 would either re-group with some MWC and AAC schools, or be absorbed by one or both of the two.
What the following schools do, or don't do, shall have a profound impact on what happens as to the power 4 idea: Texas, Oklahoma, Kansas, Florida State, North Carolina, Virginia, NC State, and Notre Dame. Others that could influence the process in a major way include Oklahoma State, Clemson, GT, VPI, Miami(Fl), and Duke (tied to UNC), and even West Virginia by making a move as a catalyst.