While the rest of the college football world would like the Notre Dame football program to join a conference, the Fighting Irish continue to pride themselves on their independence. That continues to be the case, even as the ACC continues to try to pull the Blue and Gold in closer. One potential move is to make ND an unofficial member of the conference, whether they want it or not.
The SEC's announcement that it will play 9 conference games starting next year could start a domino effect. The ACC is said to be looking at moving to 9 conference games as well, but things are more difficult because of the number of teams. That has some believing the ACC could count games against Notre Dame, even if they're not a real member of the conference.
How an ACC nine-game schedule could impact Notre Dame football’s independence
The Notre Dame football team has long had an agreement with the ACC that involves scheduling games against members every year. The Irish have even expanded that agreement somewhat with a set rivalry with Clemson. There's also the longstanding rivalry with Stanford (strengthened now that they've moved from the Pac-12 to the ACC).
With 17 teams, it's not as simple as adding a 9th conference game. Which is why one option would be 12 ACC teams play nine conference games, and the remaining five ACC teams would play only eight, but count their game against Notre Dame for their ninth ACC game.
The biggest drawback to that is Notre Dame is already playing those ACC opponents annually. So whether it counts as an ACC game or not is irrelevant since the ACC wouldn't be adding any new games with Notre Dame, it would not increase the league's media rights value.
However, the ACC making the same move as the SEC and Big Ten (which already play 9 conference games) might be more important than the added media rights of one game. Notre Dame football would then become an unofficial member of the conference, while still maintaining its independence. Something it continues to find most important, even in this new era.