Actually there's some evidence that later in his life, Marx came to the conclusion that it was possible to transition from feudalism to socialism.
This is a pretty interesting look at the class structure of the 19th century Russian left. This presentation is about 90 minutes long, but time well spent.
For me, the 20th century is actually perfect vindication of Marx in that regard.
The Russian Revolution was defeated, but its "socialism" -- really state-led rapid capital accumulation -- became the model for swathes of the world that had missed out on in industrializing in the 19th century.
In the west, private capitalism emerged out of feudalism. Later, in the rest of the world where the private capitalist class was too weak, and the working class was too small for socialist revolution, state capitalism replaced feudalism.
Gorter predicted this quite clearly in 1923:
"But given that the proletariat, large scale industry and modern capital are far less powerful there than in Russia, the revolution will certainly establish a nationalistic capitalist state, even more certainly than in Russia. It will be the same in Asiatic Turkey, Persia, Arabia, Afghanistan, etc., where there are no modern proletarians (outside the few ports).
"When Russia was forced to introduce capitalism despite its heroic and far sighted proletariat, the issue was also settled for the Asian countries undergoing their revolutions."