Since the election there's been this weird back and forth about whether Trump voters were motivated by The Economic Insecurity or by The Racism. This is yet another proxy battle in the 2016 primary battle between Bernie The Racist Who Thought Economic Justice Would Solve Racism and Clinton The Neoliberal Who Really Hated Racism (this is caricaturing the arguments so do not get mad).
I think it's important to note that the average Trump voter isn't actually an unemployed coal miner, because facts matter, and the portrayal Trump as Working Class Hero (sometimes they remember to write "White") is silly and wrong. Trump's base are not the marginal voters who switched to him from Obama, they are the same Republicans who vote Republican every 4 years.
But as for the "but they're racists!" argument. Yes, yes they are. People who are racists generally vote for Republicans. Some (many?) of Trump's voters were motivated to vote by the racism specifically, though many of those people would have voted as they always do anyway - for the Republican.
So what do Democrats do about that? If you just dismiss the 2016 election as "but...they're racists!" Then? I mean, what's the answer to that? This is about 2018, not 2020, because the world probably won't even exist by then.