I'm not sure they will see a huge advantage to joining a bunch of Midwest "Dwarfs." Yes, Kansas is a basketball blue blood, which Cincy might care about, but at the same time they have Memphis in the AAC (though it may be smart for the Big 12 to go after Memphis, as well).
The question is how much the new Big 12 TV contracts pay. I'm not convinced it will be any more than what the AAC gets, with no major draws and no real ownership of any population centers (TCU and Baylor are Texas, but are still dwarfed by UT, A&M and even OU). In fact, Kansas is likely the only state that would largely be "owned" by the Big 12.