pretty sure the fish eaters would wind up in the east with their buddies, Michigan, Michigan State, Penn State, and the Hoosiers
the west would be forced to take Iowa State, Mizzou, Kansas, or the Sooners
Careful about saying Mizzou to the B1G west, that seems to ruffle feathers. (I think they would be an apt addition.)
ISU is never going to get a B1G invite. The conference is really a TV network masquerading as a conference and they want to expand viewership. Iowa State is from a small-population State and they aren't even the main team in that state.
Kansas is more likely because at least they are #1 in their state but Kansas has a very small population (2.9M, 35th state).
The Sooners are more likely because Oklahoma has a larger population (3.9M, 28th state) and because OU is an obviously much bigger brand than Kansas.
Mizzou seems to make sense. Missouri is adjacent to three current B1G states (IL, IA, NE) and has a much larger population then Kansas/Oklahoma/Iowa (6.1M, 18th state). The thing that makes Mizzou seem unlikely is that they practically begged for an invite before they joined the SEC and the current B1G leadership completely ignored them.
I still think that the Conference would rather expand East. If they had any interest in expanding to the West then it would seem that Mizzou would have been invited when they begged for it a few years ago. I still think it will be UNC and one of the VA schools (UVA or VaTech) but I could see them taking ND instead of UNC.
Ultimately, I don't think ND makes any sense. They have a certain brand/draw football wise but they don't "own" any media markets the way that most of our schools do. Additionally, I do not think that ND has the academics to help the B1G's academic arm. Now, any ND fans reading this will be astounded by that statement or perhaps think that I am nuts but hear me out:
Notre Dame is a great undergraduate school but the BIG money in academics (bigger than the sports/TV money even) isn't in being a good undergrad school. The B1G money in academics is in graduate programs and research. As an undergraduate school, Notre Dame would be one of the best in the B1G. As a graduate/research institution Notre Dame would be dead last by a significant margin in the B1G. I don't mean this to pick on ND, that just isn't their focus. If the B1G wants to improve graduate/research academics (and they do) there is absolutely no contest between ND and any of the following: UVA, VaTech, UNC, or even OU or Mizzou.