They will conclude that Trump’s win was the result of a Russian hack, and will change NOTHING about how they go about their business.
They’ll get their clocks cleaned in 2020.
They will attempt to do to Trump what they did to Bush. They will wait for Trump to make a mistake, or to take an action that becomes unpopular, and/or for the next recession, and they will then engage in 24/7 hate speech and libel, attempting to win the next election with a purely negative campaign.
The media loves to explore the internal strains in the Republican coalition. The Democrats' problems are at least as severe. They have a black radical group that wants a tribal party organized around a program of racial privilege. They have a radical feminist wing that hates men. They have a sexual revolutionary wing that wants the destruction of any and all limits to sexual behavior, and wants this without guilt, which brings them into conflict with anyone (including many feminists) who object to sexual anarchy and predation. They have a Stalinist wing that wants to kill the kulaks. (I exaggerate only slightly.) They have an anti-religious wing that works actively towards the suppression of orthodox Christianity and Judaism. They have an anti-democratic faction that does not accept the legitimacy of political opposition and seeks to limit political speech. They have an internationalist and open borders faction that desires the eradication of the American national identity. And that list is surely not exhaustive.
The ONLY thing binding this coalition together is hatred. It is a functional necessity for the left to find an Emmanual Goldstein; almost anyone will do, and the target will shift as soon as the first target has been destroyed. Leftist campaigns are the functional equivalents of two minute hates.
The question is, are there enough Democrats who don't want to go down this road to pull the party back from the abyss. They're pretty far gone as it is.