One of the good things to come out of this is that positions like universal health care, free higher education, a livable minimum wage, etc. are now much more popular than 10-20 years ago, and terms like socialism are no longer taboo in the political mainstream. I also believe that Democratic wins down-ballot during the Trump administration will help them rebuild their bench, and that there exists the potential for an FDR-type candidate to emerge and win in 2020.
but will that translate into actual results? There's a natural tendency for public opinion to rebel against the prevailing orthodoxy. Trump happened because people got mad over Obama's policies, and now policies strongly opposed by the Trump administration might be gaining ground as part of a back lash. But as soon as the Dems get back into office who is to say things won't swing back the other way? Or if they don't, who is to say that whoever is in power makes good on their promises?
People seem to forget that Obama ran in 2008 significantly to the left of how he governed; his campaign message was a response to a (correctly) perceived ideological shift in the Overton window after nearly a decade of Bush (and more than 20 years of neoconservatism, when you consider that Reagan, Bush I and Clinton all championed it). When he got into office he governed as more or less a centrist who leaned to the right on economic issues. And yet within two years he had already been constantly put on the defensive for being a "socialist" and "far left".
I would love to be optimistic, but honestly I can't. Maybe it's just my personality, but I don't see Trumpism or its long term consquences simply giving up without quite a fight.