Pete Thamel of The New York Times is reporting that the Big 12 conference will not make a move on potentially inviting BYU, West Virginia or Louisville, implying that any move the conference makes won't come until the Tigers make their decision.
Per Thamel, with the just-announced invitation to TCU, the Big 12 could either stay at 10 teams including Mizzou (temporarily or permanently), or use all the three rumored teams in consideration to bring the Big 12 back to an actual 12 team league.
As always, everything in college sports hinges on word from upon high in the SEC's Birmingham offices. With news that the SEC isn't sold on Missouri as their 14th member and are considering holding out for a better option (even as schools complain about a lopsided year of scheduling with 13 teams) there's no clear indicator that the Tigers are a lock to leave, or if they do, anytime in the immediate future.