IIRC, the Hawaii rule allows applies to all games played outside of the continental US. So when Notre Dame played Navy in Ireland, they had the option of scheduling another game. They didn't.

If the 13th game becomes a pre-req for post-season play, they will want that extra game. An annual international game could become a regular thing for ND. I've heard rumors they want games in Ireland, Mexico City & even Italy. BYU wouldn't be ND's first choice for an opponent. But they'd be a reliable one.

Let's get this out of the way: no one thinks Notre Dame is our "buddy". Like any other program, they are motivated by self-interest. I am skeptical that we'll ever see them in Provo. An international game is another story. Especially if ND needs it for playoff access.