Missouri would be a good bet, but then what would happen to the MO-KS rivalry ? Notre Dame won’t join anything because they’re doing well as an independent. The Rust Belt colleges further east don’t have the following that Ohio State, Michigan and Iowa have.
I still think Texas might be just the school to break new ground.
I think the Texas state legislature has to approve a move by any state Texas school and I don’t think they would ever approve Texas without Texas A&M and maybe even Texas Tech.