If any ACC team goes undefeated, they will end up in the Final Four 90% of the time. Even with one loss, their chances are decent.
I wouldn't overstate the SOS concerns of FSU and Clemson, both are much more concerned with staying in the same ballpark on a TV revenue basis with the SEC and other conferences. The B12 membership rumors for both will likely end up helping the ACC get their ESPN contract renegotiated to a desired level and both will likely stay put. Their chances of getting to the FB Final Four are better in the ACC than the B12 if both of them would get their act together on FB. Their issues in recent seasons have been self-inflicted, it hasn't been due to their ACC affiliation. Boise St and TCU certainly have not had their conference affiliations hurt them in recent seasons, both would have made the Final Four at least once in recent seasons.