If Miami wins the rest of our games, we'll be in the ACC Championship. If we don't, we won't, and we won't be in the playoffs either.
It is VERY unlikely that we make the playoffs without also making the ACC Championship.
I have watched this league for enough years to know that. This time of year, everyone is always playing out "what if" tiebreaker scenarios, but I can guarantee you that it will work itself out, it always does.
Virginia, Georgia Tech, Duke, etc will not go undefeated from this point on. And that's what would need to happen for OP's scenario to play out.