The SEC has already pulled ahead of the pack when it comes to athletic dominance in many prominent college sports. They generally have the best teams, most resources, and best fan support in football, baseball and softball, among other sports. Other conferences have competitive programs of course, and none of this means every school in the SEC is better than all schools elsewhere. But on the whole, the SEC is the big leagues compared to other conferences.
Two of the programs that could match up with the SEC in terms of competitiveness across sports, resources, and fan support, are Texas and Oklahoma. Those schools appear poised to leave the Big 12 for the SEC.
Not only would that further cement the SEC as the most prominent conference in major college athletics, but it would completely weaken the Big 12, making that conference nearly irrelevant.