I have actually wonder this many times. DFW is the second biggest metropolitan area for SEC alumni next to Atlanta, so TCU would be a very attractive option for SEC.
However, I would lean toward Bama, Florida, and LSU not wanting to add a team consistently good enough every year to be a thorn in their side. Also, while we would get a fatter paycheck every year, our record would not be as good as in the MWC. Our typical 10-2/11-1 season in MWC would be more like 9-3 in SEC, at least for a few years.
Anything is possible, but I think we are as invested in the MWC future as the rest are, and hopefully the same goes for the Utes!