Yeah, but in the real world, these PAC-12 negotiations mentioned in the article will be dynamic, not static, and will include a lot of "what about's", as in the network putting out their initial offer, then the PAC-12 starting in with "what about if we did this, or did that"?, or "what about if we added 2, 4, or 6 more teams? how many do you guys think would be the "right number", and which schools would you think would work the best for an expanded PAC-12? "What about any suggested changes to the PAC-12 Network"?
If after all that, the network's final offer is still weak sauce, then you might see some PAC-12 defections. But if the network(s), in their "negotiations" essentially gave the PAC-12 a road map to a bigger payout, they would more than likely follow it, which would likely involve expansion as part of that. If they were to decide to add some teams, those teams would know ahead of time what was coming down the pike and would probably give the Big-12 their two weeks notice, long before the Big-12 would be able to poach some disgruntled PAC-12 teams.