"History doesn't repeat itself, but it often rhymes."
A good portion of my second run through undergrad dealt with European politics throughout the interwar years, specifically how movements like fascism, Nazism, ultra-nationalism, and totalitarianism managed not only to gain traction, but come to be embraced by majority populations and how that in turn allowed those folks to carry out some of the most horrific crimes humanity has ever recorded.
This stuff reads a lot like that stuff. It's not a 1:1 (it more resembles the lead up to the Spanish Civil War than 1930s Germany, imo) but it's closer than I think most ever imagined. And yeah, the danger goes beyond Trump. This roadmap is simply waiting for the next GOP winner. And at some point, there will be another GOP winner.
Short of continuing massive voter turnout and... I don't know... hyper-vigilance(?) I'm not sure how else you combat this. In Spain, the pendulum between right and left governments in short succession finally broke out in civil war when Franco and the military chose a side. In Germany, beyond all the economic factors from Versailles, the left wing went after each other (socialists v. communists) while trying to fend of the Nazis electorally. Everyone is well aware of how that plan worked out.