1) The Big 12 hasn't added anyone. That doesn't mean it can't happen, it means it hasn't happened. I'm sure the Big 12 wants to wait and see what happens with the PAC but if the PAC survives, the Big 12 may shift their focus.
2) If the PAC goes down to 8 members, there's a very good chance they will want to get up to at least 12. It's why they're talking about SDSU and SMU right now, to get them back to 12.
3) SDSU could potentially joining the PAC by paying the exit fee that was agreed upon. All these contracts have exit penalties that are agreed upon. Conferences with lower payouts, like the MWC, generally have lower exit penalties. The ACC has made their exit penalties so egregious that nobody wants to leave the conference. But is that good for the ACC? The ACC schools don't seem to think so.
A couple factual errors you've made:
- I never claimed everyone in the MWC has a chance at joining a P5. This idea would probably be supported by SJSU, Hawaii, Wyoming, etc.
- Nobody compared Maryland to anyone in the MWC. The point was Maryland leaving triggered the ACC into implementing the idea that you're calling for. And with the gift of hindsight, it was clearly a mistake in the eyes of FSU, Clemson, UNC, etc.