Zero anxiety. I'm one of the few though who wouldn't mind the Big 12 at all.
BYU fans are excited about being in the Big 12 and they should be. They deserved it 10-20 years ago. They've hated the Utah / P5 / P12 stuff over the last decade and especially loathe that Utah has found success.
They cope by constantly comparing Utah to programs with exponentially more resources, talent and history and dwelling on every loss — as if every other program is winning. Smart BYU fans can see through that. You can't lose to UAB and mock Utah for losing to tOSU by a last second FG.
The thought of roles being reversed and the P12 falling apart and Utah left homeless is pure schadenfreude and sweet justice. Too tempting to pass up. That's totally understandable.
Once that thought enters the mind, BYU fans only see bias confirmation that leads to Utah in dire straits. Read CB after every Utah loss...it's this long prophesied imminent demise.
But it's never happened. Ironically, Utah happens to be the only program that has been on a slow, 30-year inclining trajectory that hasn't really stopped in any 4-year cycle.
Utah is no longer the "Wyoming" of the P12, but now the returning champion. Again. They did so by beating two top 5 teams on the national stage in consecutive years.
At this point, a conference like the Big 12 doesn't pass on the opportunity to stab the Pac-12 by taking such a strong performer...just because. It's not even a thought. They take Utah in every situation they can.
Utah would be instantly competitive where the practical competition for Big 12 expansion has really struggled.