I hope this doesn't happen, but I think in general I think every part of the country minus places like ,ME, MT, IA, and other places notorious for a D-->R shift in general would get slightly bluer.
Turnout amongst 16-18 year olds would probably be quite low too, so I don't think it would have massive implications, many would likely be duplicate votes of their parents.
Actually, the opposite is the case.
Austria is one of the few countries on the planet that allows 16-17 year olds to vote in federal elections.
Studies have shown that their turnout in every election is
as high, or higher than the overall turnout, because they deal with the election in political science lessons in school at the time of the election, engage in school discussions and therefore are eager to vote.
Not only that, the things mentioned above make them more likely to vote in future elections too, therefore strengthening the civil engagement further.
The lowest turnout is actually in the 20-30 year old crowd ...