I'm not a political swami or a genius fully in tune with the public mood, but, irrespective of how this "Trump business" plays out, I sense that Democrats need to start getting their act together - they need to play their cards right. Particularly, they have to avoid the temptation of going hard left. In 2020, they need to nominate a "likable" (non polarizing) candidate that doesn't have a history of scandal and questionable ethics. That means no Hillary Clinton, no Bernie Sanders, and no Nancy Pelosi. I listened to Elizabeth Warren giving a commencement speech to the graduating class of the University of Massachusetts - Amherst. It's clear, to me, that Senator Warren is setting the ground for a possible 2020 Presidential run. Even though I love Elizabeth Warren, I'm afraid even she will be too liberal to get elected.
Democrats need to nominate somebody like Connecticut senator Chris Murphy.
https://en.wikipedia.org/wiki/Chris_...cut_politician)
Senator Murphy doesn't carry the baggage of being too liberal. Somebody like Murphy (or maybe even Joe Biden) can get elected - especially against a staunch Republican dinosaur like Mike Pence. The ideal strategy for the Dems is to have a centrist candidate running against an ultra hard right Republican. It will also help if the Dems stress a positive message rather than trying to win by constantly stressing how Republicans only care about "the rich" and the one percent. (That "message" didn't work so well for Hillary - although it did work well for Obama versus Romney, but Obama wasn't carrying all the negative baggage that saddles HRC ...)
Above all, Democrats need to find (and nominate) a candidate that people can identify with. It's basic politics. They can't operate on the assumption (dream?) that Donald Trump is going to sink the GOP. Republicans will come to their senses and torpedo Trump long before he destroys their party.