The SEC doesn't want any thing to do with the West Coast. While the valuable schools in the Pac 12 don't want to join the Big 12. For the B1G, the top Pac schools will always be there. 

But the ACC schools the B1G might be interested in might not always be available if the SEC comes knocking. Mizzou was always a school rumored to be on the B1G list of candidates, and I think having the SEC pick them was a wake up call for the league. With the B1G already in Maryland and NJ, adding UVA, UNC, Duke, and one of Georgia Tech, Pitt, or even BC would be a much better fit than any Pac school.