They are not moving down to PAC or ACC for less money and bigger geography. The SEC and Big10 are doing just fine in the catbird seat as is. The Big12 “instability” is simply not something that concerns them.
I would keep an eye on the PAC though. Many have felt for a long time that equal revenue sharing would not sit well with USC, UCLA, and Oregon over the long haul. Ultimately, that is what disrupted the Big12. Texas was heavily subsidizing the conference while the SEC was cashing in. Eventually, something has to give in PAC country because they are not looking at a big contract in the next round compared to others.