Possibly, but a few issues that make this tough
1) if Oregon and Washington leave, the remaining PAC8 aren’t in a position to poach from even the new Big 12
2) if Oregon and Washington haven’t yet left, but are openly considering it, then teams are going to be hesitant to join a conference in flux.
The key is first playing defense on those two programs. If Oregon/Washington make a statement that they’re committed to the PAC and will be staying (and/or it becomes clear the B1G isn’t interested), then the PAC12 can go on offense. Right now they need to be working to hold onto Arizona schools, Colorado and Utah until that happens