As long as the ACC exists and/or good programs aren't gobbled up by another conference, ND can be independent. There's talk of FSU, Clemson, Miami, UNC, UVA VT going here or there, but in the eastern half of the country (if that still matters), there are still decent programs that are unlikely to just fade away.
GT, NCST, Pitt, etc aren't the same as Wazzou or Oregon State. They matter and unless any future playoff requires a conference championship, these programs may hang on. They're not the steak or potatoes, but they're not nothing, either. ND is an island and if there's an archipelago of teams like it, it may extend their isolation.