Have it on pretty good authority that the B1G's primary targets in the ACC would be UNC, Duke and UVA (though we are probably 3rd among those but viewed as an attractive package with the UNC rivalry). They are not really interested in having non-flagship schools in SEC country - just doesn't fit the conference culture or their strategy vis a vis athletics.
One long-term spitball scenario apparently calls for adding 6 teams - ND, UNC, Duke, UVA, Stanford and Cal. Teams would be grouped in 4 pods of 6 teams each, primarily for non-revenue sport travel purposes but with some influence on FB and BB scheduling. Another interesting proposal was to have a set schedule of 14-16 MBB games plus mini in-season tournaments of 4-8 teams (1-2 from each "pod") over a weekend to get to 20 conference games overall.
Proposed Pods as I understand them:
Duke, UNC, UVA, Maryland, Penn State, Rutgers
Ohio State, Indiana, Purdue, ND, Michigan, Michigan State
Illinois, Northwestern, Wisconsin, Minnesota, Iowa, Nebraska
USC, UCLA, Stanford, Cal, Oregon, Washington
There is a lot of logic to the above IMHO but it all hinges and landing Notre Dame and going from there.