As of this writing, Trump has drawn fewer votes than McCain in 2008 and substantially less than Romney in 2012. He even has less than Hillary. So I'm not sure I agree with this analysis about rural voters - at least not with respect to it being anything unique to this particular election.
What seems more likely is that there was an enthusiasm gap for Hillary Clinton as a candidate. It's about the electoral college in the end, and a Democrat like Hillary, who lacks the charisma of Obama, was going to have to bring out minorities, young voters, and college educated voters in droves to win. She simply was not able to sufficiently do this.
To win the rural vote back, the Democrats need a different kind of candidate, none of the ones that they have offered have been able to do this since 2000.