USC seems to be backing away from playing Notre Dame every year. Scheduling and travel concerns with USC now in the Big 10 seem to be an issue as well as how difficult USC's schedule is some years. Next year, they are scheduled to play at Indiana, at Penn St, Ohio St, Oregon, Washington, and possibly Notre Dame. After the tentative 2026 game with Notre Dame, ND and USC do not have any future scheduled games.
Notre Dame's relationship with the ACC locks in 5 games per season which means Notre Dame has to schedule 7 games. If Notre Dame went fully independent, I would think they would have a tough time scheduling 12 games with a reasonable number of tough opponents each year. Scheduling difficulties is one of the reason Notre Dame signed up to play Clemson every year.