Mizzou's board of curators (I guess it's just one big museum in Columbia) meets today to either agree to commit to the Big XII (and ostensibly sign on to the 6 year pact to grant to the conference all 1st and 2nd tier rights put forth by David Boren of OU and the new Big XII commissioner) or to potentially vote to withdraw and ask for an invite to the SEC. I think it's 80/20 former to latter, but one never knows anymore.
You couldn't begrudge an Mizzou move to the SEC at this point, but if their real goal is the Big Ten, and the Big Ten does eventually go to 14 or 16, Mizzou has to kinda like its chances for being one of the teams that's picked up, especially if the ACC Solidarność is as strong as it currently seems. But it would certainly be a calculated gamble to wait.
If the teams stay in the Big XII, they'll have to grant their 1st and 2nd tier rights to the Big XII for a period of 6 years, which is one year beyond when the contract signed in 2010 expires, I believe. That sounds like a huge ask, but it's not much different, and for many fewer years, than the Pac 12 and Big Ten have tied up the schools first and second tier rights (and in the case of the Pac 12, third tier rights, too). The key difference, of course, is those conferences aren't going anywhere.
Meanwhile, the Big XII will have equal first and second tier revenue sharing now. A red herring of an issue this whole time, but there it is. It will be set up just like the SEC currently is.