Progressive and conservative are an odd nomenclature nowadays. Both "sides" have large populist elements that share a hatred (and conspiratorial paranoia) of globalism and "the elites".

In this respect, ANTIFA and alt-right white-nationalists have a lot more in common than they'll admit.

That white nationalists (at the grassroots, even before considering what ends they might be being manipulated to serve) are about concentrating power in a specific subgroup rather than distributing it in an egalitarian manner is, well, painfully obvious from their overt label.

It's true that just as both those seeking a broader distribution of power and those seeking to move it from the aristocracy to the mercantile class shared a small degree of common interest in the downfall of feudalism, the anarchocommunists and other leftists at the heart of Antifa and the White Nationalists in Trump's base might have something of a common opponent in at least some segment of the current cosmopolitan corporate elite, but that is a weak and transitory common interest, and their general interests are fundamentally in near-polar opposition.

There is no contradiction between the desire to achieve a flatter distribution of power, while also concentrate it in a specific subgroup. It's exactly these things that are the goals of Steve Bannon's wing of the right.

The commonality between the anti-fascists (or whatever they want to call themselves) and white-nationalists is neither weak nor transitory. Their common enemy is liberal democracy, and their preferred strongmen will not always necessarily be different. Take a glance at places like Serbia and Russia to see this in action.

Back to the original point though, I think progressive vs conservative is not a useful basis with which to analyze these movements.

Progressives are at war with everyone rather equally; so I don't see the utility in insisting on a unidimensional axis. They claim to be opposed to white nationalists specifically, but then they go on to categorize literally everything to their right (including liberalism) as white supremacy. And I say "equally" because progressives spend more time criticizing moderates than the extreme right.

Further, I question the sincerity of the progressive commitment to equality, since the mob comes after anyone who points to data that don't support their apocalyptic narrative.