I have no idea whether the PAC will or will not expand, soon or ever.
I must say, all of these rationalizations for why it should are funny as hell. People hoping beyond hope that media money proves to not be as important as it clearly is in determining expansion candidates.
Consolidation is as likely as expansion. There are schools that have no business being in P5 leagues.
The day of the Super Conferences is nearly upon us. Big schools, with big alumni bases that are willing to spend and support the programs, will all be grouped together. A league with somewhere between 40-60 teams in four to six divisions will emerge, modeled on the NFL system. That will be that.