If BYU stopped playing Utah (especially with the Big 12 invite) it wouldn't hurt BYU's relevance. They'd play their conference and another solid P5 or two and then some easier games.

And Utah would do the same (maybe even slightly easier with the Alliance depending on how that all shakes out). Neither would be massively hurt by not playing the other.

But for both it would be unfortunate to lose a charged, meaningful game. If BYU replaces it with a game against UCLA, Miami or Arkansas and Utah gets Michigan or Florida or whatever they'd be fine, but it is fun to have rivals that you compete regularly with.

That's one reason I'd like to keep scheduling Boise semi-regularly. We don't NEED them, but it would be a fun game to play.