BYU's no-Sunday policy is not insurmountable for the Big 12
Here's an article published 5 years ago in The Oklahoman that goes through, sport by sport, the changes that would be needed to accommodate BYU. The conclusion? A hassle in some minor sports but worth it.
The Big 12 will vote on expansion this summer, OU president David Boren says, so it’s not a bad time to start seriously vetting candidates. Not just throw out the names of schools, but look closely at the issues. Brigham Young has remained a hot candidate since the first Big 12 exodus in 2010.