I would assume we will hear about the Pac-12s future sometime later this year. Those TV contract negotiations will take place, and stuff will leak. I'll be really curious to see the chain reaction that creates.
I don't think the Big 10 makes any moves until the Pac-12 is "settled."
I think you're right, but also in combination with OuT negotiations and CFP changes. It's all one 5 foot diameter ball of tangled christmas lights.
If the Pac12 gets a good contract (40-50M per team) then we might see things stay fairly much the same as they are with a P5 setup. If they get a number that is disappointing, then there will be a lot more momentum for USC/Oregon/etc to want to do something else, and then all the weird stuff is in play.