Maybe. I just think that as long as ND has a path to the CFP as an independent, they'll stay independent.
But if the power 4 conferences want to press the issue, all it would take is to keep their members from scheduling ND. So ND could make the playoffs with a schedule full of G5 or lower schools, but their fanbase wouldn't be happy with that. Now with USC n the Big10, what would ND's schedule look like if they restricted playing them in non-confernce games?