To be honest it's not a meltdown. It's kind of funny from our perspective because for once we're not the punching bag.
If we're being honest here, the PAC is in real trouble. The PAC 12 already made less than the Big 12 from their contracts and now they lost their two biggest draws. The Big 10 has said they aren't adding any more PAC schools, and if they were going to do it IMO they would have already done it.
As for Big 12 schools going to the PAC, well the PAC's grant of rights are over in 2024. That's why USC/UCLA can leave so quickly. Big 12 GoR aren't over until 2026, and like we've seen with OU and UT it's not exactly easy to get out of those. So no teams from the Big 12 are going to the PAC until then. Which means that the PAC is going to be negotiating their next TV rights deal for 2024 without USC and UCLA and without anybody else really. I think they are utterly boned.
As for the ACC, they signed a GoR through 2036 and they have the worst TV contract in sports right now also going through 2036.
Some enterprising lawyer is going to be really working hard to find their way out of this stuff but again, if it were easy, OU and UT would already be out of the Big 12.
TLDR: I obviously could be totally wrong, but I think it's much more likely PAC schools will be joining the Big 12 or there could be some kind of merger.