Let's say the Soviet state still rises in 1917, but is defeated by the Whites around 1920. In that scenario,
-Germany has still been defeated and is teeming with discontent and revanchism against the nations to the east.
-The economic problems faced by interwar Germany are still in the picture.
-Radicalized veteran militias are still in the picture.
-The new Russian government might even have some vague socialist aspects. And either way, it can act as a bogeyman to German nationalists because of its key position in the new order. Not to mention the traditional chauvinism against eastern Europe.
-The Soviet state is defeated, but it was around long enough to give certain sectors of society a nasty shock. Together with the threat of increasingly popular socialist movements, this could make these sectors of society willing to fund and support political, er, alternatives.
In these circumstances, I don't see why the rise of a far-right party in Germany should be considered impossible. Much less likely, maybe, but far from impossible.