I see two possible outcomes. The conference will decide to expand counciding with the Big Tens new contracts. A CCG will be enacted and there will be a significant bump in payouts. A conference network will be arranged that gradually phases in the LHN. Either the networks will renegotiate the Big 12 deal to extend much further out, or in 2025 the conference will redo the existing contracts with a much higher payout than possible now. In 2025-2027 the new BIG 12 will work to add ACC schools as that conference runs out of financial means to keep pace and FSU and others decide to move on.
Or, the conference will not expand, leading to yearly renatches which will knock the BIG 12 out if the playoffs numerous years. Negative press will escalate, recruiting will drop off, the conference will be offered a lowball contract after years of non competitive teams nationally and lower tv ratings than others. OU will have been in the planning stages of departing for years and will do so with OSU to the Pac 12- quickly followed by UT and Texas Tech. Kansas and Iowa State will be absorbed in the Big 10 as they are AAU. Baylor and TCU will make the SEC a 16 team conference. Kansas State and WVU will be left searching for homes as the ACC works to add UConn and Notre Dame to finish off their 16 team league.
You will be claiming all the while this is in the works that the ACC is falling apart any day now so the BIG 12 should hold off doing anything.
Regarding rematches, you are totally wrong. Number 1 you are assuming the higher ranked team is going to lose which at its premises is just silly.
Number 2, had the big 12 had 10 team CCG game last year, the winner of that game BU or TCU would not have bumped from the playoff. rematches are going to happen, it is just 100% sure with the BIG12. The PAC has a 75% chance of a rematch, and you don't see anyone running around crying the sky is falling.
No I won't be claiming the ACC is falling apart. What I will say is if the BIG expands it will do so with ACC teams either a combination of UNC/DUKE or 2 from VT/UVA/GT, and not from the BIG12.
Oh, and OU isn't going anywhere.