Interesting question: who should the Democrats run in 2020?
If Trump does decently well, he'll have a huge advantage going into 2020, and the Democrats won't run their starter. But, assuming that Trump is not popular in 2020, who will be the Democratic candidates?
Clinton is out. Losing candidates have never tried a second time because of all the existing negativity. Although, I'll be the first to admit that this has been an extremely unusual election, and the fact that she looks to have won the popular vote by perhaps 2 million votes may change that equation. On the other hand, she'll be older than any other candidate to have ever run, except for Trump himself.
Sanders will be too old as well.
Al Gore? Interesting possibility. He'll be older than any previous candidate at 72, but younger than Trump. He had no serious skeletons in his last run, and as far as I know, he's not picked up any new ones. He's boring, but well liked, and he did try to warn us about climate change. On the other hand, he made a lot of short term warnings that haven't played out.
Elizabeth Warren? Would the party try another woman?
Andrew Cuomo? Al Frankin? Jon Stewart? (Why not?)