I'd think that the only thing holding the Big10 back from announcing them is that they want to wait until after the UC regents vote on UCLA. To have the PAC implode with those two might prevent them from approving UCLA from going.
Once UCLA is in the clear, they'll pull that last domino and watch the whole thing tumble.
The thing is though, if the regents are looking at it objectively and not as fans, they'd still probably have to say yes to this.
The pac 12 is far behind as it is, even without losing these teams.
The regents can choose between having one program that is in the Power 2 or having zero. There's no option for both.