> The answer is to continue to encourage progress but increase redistribution efforts to help the people who are left behind.
This is the Bernie Sanders answer to the same question. For Sanders to get as close as he did to nomination would have been as utterly unthinkable even 4-8 years ago as Trump's nomination would have been. Sanders rode the same wave, offering a left-wing reaction to the decline of the American interior vs. Trump's right-wing reaction.
While I personally can't stand Trump, I'm actually a bit concerned that if he loses to Clinton we'll be facing a real full-blown gloves-off fascist in 4-8 years. The kind of systematic decline I described in my OP is historically the precondition of fascism. I have a friend who's been predicting this for years, calling this "Weimar America."