The B10 will not take a non-P5 school. No way. I can see BYU/Cincy being an intriguing option for the B12. I can see the long term viability of the ACC, but not the B12. The actual schools in the B12 are not at all similar and the league is too Texas-centric.
Especially paired with the common knowledge that Oklahoma and Kansas were in the group that wanted out of the B12 a few years ago, I see them as the most likely candidates for the B10. If I had any choice though, I'd probably very slightly want them over the UNC/UVA combo (assuming Texas/ND are not options). OU and UK don't offer huge markets, but they are national brands and I remember reading an article that TV can charge pretty much whatever rates they want in those two markets. We already have the DC market anyway.
When the B10 was first looking at expansion, I was a huge Pitt advocate. Now I have a much better idea of what really matters to the university presidents, and how the TV deals work. Pitt would not add anything to the B10. Literally. Between OSU and PSU, Pittsburgh is already charged first tier rates.
Read through the following blog. It's really good and where I got the foundations for my a lot of my above thoughts.
http://frankthetank.me/