It's not just a bowl-contract, power, prestige and money thing; the Big 12 actually has a vote within the Autonomy governance structure. There is zero reason kick out Kansas, Iowa State, Texas Tech, TCU, etc. while to Vanderbilt, Louisville, Wake Forest, Boston College, and Illinois retain a vote.
The Big 12 is highly likely to have a worse TV deal and bowl lineup come 2025, but the seat at the table remains.