One interesting scenario I've seen is Mizzou joining the B1G, leaving space for OK State to join Texas and Oklahoma in the SEC.
Would be an interesting move as (assuming KU joins) they'd have a couple of built in rivalries here with us and Kansas and some old Big XII history with Nebraska. I don't know if B1G goes for it as it's wouldn't be a wholly new market (St. Louis and KC would theoretically be covered by us and KU), and they'd probably have to make it attractive for Mizzou to leave the cash cow that the SEC is about to become.
If Mizzou “was available”, I think the B1G takes them in a heartbeat. They satisfy every condition the B1G would want. I just don’t see how Mizzou becomes available though. I don’t think Mizzou wants out, nor do I think the SEC has any reason to want them out.