If TX and OU leave, I am going to go out on a limb and guess the average payout for the Big12 would decrease--by a lot. There is a reason why they get a disproportionate share today...they bring in a disproportionate share of the revenue. So that advantage goes away.

And there are really no other advantages of the Big12 over the pac12 for those schools. It would mean longer travel, less desirable destinations, a major downgrade in the weather (miserable heat & humidity in the summers for the southern teams and ice/cold in the winter for the northern teams), no conference games against marque (USC and probably Oregon still qualifies) in-conf opponents.