I think it’s unlikely the B1G expands at all if Notre Dame stays independent. It’s simply too hard for an addition to be worth it financially at this point; the bar is so high.
The corner schools come here and then Oregon, Washington, Stanford, Cal have decisions to make:
1. Add four schools to rebuild the Pac-10: San Diego State, plus whichever other ones the TV networks tell you to add and that the academic snobs can stomach. There’s no way this is worth much money though. But maybe SDSU, Colorado State, SMU, and whichever other Mtn West school is respectable academically would be preferable in a world where the Pac-10 keeps a Rose Bowl bid and the coastal schools don’t have to associate with BYU and Baylor. The new additions could be on heavily reduced shares of TV money - still higher than Mtn West/AAC, but much lower than what Oregon gets.
2. Consider independence (more likely for Stanford and Oregon). Would be a huge risk.
3. Come crawling to the Big 12. We will already be at 16 and this would put us in an intriguing position of strength.