Both would be pretty far down the list.

Secondly, if somehow the mega conference thing failed to such an extent that a version of the PAC came back into existence that would mean the Big XII would still be around as well.

The obvious teams for expansion are:
Notre Dame (BIG or SEC but more likely Big)
Duke & North Carolina (BIG)
Stanford & Cal (BIG)
Clemson (SEC)
FSU & Miami, Fl (SEC or BIG)
UVA & Va Tech (More likely SEC)

Then the best if the rest:
Kansas
Colorado
Pitt
Arizona Schools
Texas Tech
Utah schools
NC State
K-State
Oklahoma St
TCU (but but but DFW market - please we all know they own a relatively small percent of their own market)
Baylor…
Everyone else