It's an interesting argument, but I think what makes it more interesting is to consider it in the light of 2016, and the aftermath.
What Trump represented, for good or bad, was an actual departure from business as usual in Washington DC. His election was as scary to the entrenched Republicans as it was the entrenched Democrats. Trump represented a successful revolution in the Republican party of the loping, uncouth, blue collar masses of the flyover states and he won against the epitome of the entitled, Business as Usual political class in Washington.
The average working class American was sick of it. The Republican base was tired of hearing "wait until next election" whenever it seamed like it was time for their concerns to be addressed, and the Democrat working class in the Midwest was tired of unanswered promises, and fail policies when Democrats attempted to address them.
I think, if nothing else, Trump turned the tide in the election with one statement that he almost certainly didn't write himself: "It used to be that they built cars in Flint and you couldn't drink the water in Mexico. Now they build cars in Mexico and you can't drink the water in Flint."
That line cut to the core of what pissed off the rust belt more than anything else. Creeping, persistent, Democrat lead decline and all Hillary could offer them was "well, get a different job!" .. her "let them eat cake" moment.
Trump is still seen as a thorn in the side of establishment Washington, and Establishment Washington is a term that is increasingly associated with Democrats now that so many anti-Trump Republicans have bailed from politics in favor of the chattering class. That isn't a good place to be for Democrats, and I think, given the severe distrust of Washington in both parties, being the party of bigger authoritarian government programs will not serve them well in 2020.
one last point: Sweeping government benefits is an effective political selling point during recessions when the electorate is feeling most vulnerable and looking for easy hope. That is increasingly looking to be an unlikely scenario in 2020... and yet the Democrats keep pushing forward like they'll get a recession just in time for election day.