from ND's perspective, a show-off game in case they're in CFB/NY6 contention at the end of the year. Most of the teams they'd be competing with are playing in their conf championship game that weekend, so while BYU isn't typically as good as these CCG opponents, they're usually respectable and are better than sitting at home while their competition for a big bowl game gets to play a CCG vs a solid opponent.

The only downside I could think of from Notre Dame's perspective is that they always have a long road trip the week before to California for either Stanford or USC. So maybe they think the upside from beating a 7-5ish BYU isn't worth the risk of losing the game (they'd usually be heavily favored, but a road trip to Provo the week after a long road trip to California is tough on most teams).

Maybe I'm wrong and from Notre Dame's perspective it's not better than nothing. Maybe we'd need to make the conf championship weekend games in South Bend or neutral, but close to South Bend (Soldier Field? Indianapolis? Detroit) and the games we play in Provo (and maybe any neutral in LV?) would need to be September or October because of the travel concern I listed. I'd still probably do it, it's so tough to get good November games. Then use our extra in-season bye week on the week before Boise St or something like that.

I dunno. Maybe this is just a non-realistic far-fetched idea like the best of G5 conference suggestions.