The Pac 12 could have had something with a Pac 10-SWC merger after Texas, A&M, Tech, and Baylor left for the Big 8. Having both TCU and SMU from the Dallas-Fort Worth market as well as both Houston and Rice would have been huge thorns in the Big 12's side. The Pac 14 would have probably gone to 16, and it's possible Colorado might have left the Big 8 to go to the Pac 16. Utah probably still would have got the last spot.
Even with two divisions, the Pac 16 could have guaranteed its members a game in Texas at least every other year.
That's an interesting thought. My guess is that it never had any steam because at the time most if not all of the left behind SWC programs were playing terrible football at the time and not in a position to challenge their instate Big 12 rivals who left them for dead. Those 4 didn't even have enough sway to bring in the football playing Metro/Great Midwest schools Cincy, Louisville, Memphis, Tulane, and Southern Miss. Houston ended up with them when they reunited as C-USA and TCU spent 4 seasons with that group before the Big East raided them.
I think in the early '90's the Pac 10 looked at going to 12 with Texas and either Colorado or A&M but that obviously didn't go anywhere.
As for my proposal--I think that everyone would get at least one away game in Texas and California. I think rather than cut and dry divisions they'd do scheduling pods:
4 Pacific Northwest schools
4 California schools
6 Texas & Oklahoma schools
With a 9 game conference schedule the 4 team pods would have 6 additional slots while the annexed Texlahoma 6 would have just 4. That gives everyone a chance to play in both of the big recruiting states at least once. The Texas schools probably don't visit California very often and vice versa but they could find a way to make it work.