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The Black Death is certainly a contributor to the end of feudalism, but it is not the only thing involved and is somewhat indirect. I would suggest that plague has more to do with sowing disillusion to the effectiveness of the state and church at the time.... Much later, people began to see that the feudal system is what caused the Black death to be so black, but the beginning of the end for the feudal system did not come until the Renaissance (c. 200 years later).
Some things to consider....
The Black Death occurred in the 1350's, and afterward, the nobility had a less tight grip on the population, but it also caused a huge increase in religious fervor. This contributed to things like the inquisitions and the witch-trials (used as tools to re-establish the role of nobility and the church), but ultimately further developed political disillusion.
The printing press was also a huge factor, invented in 1440's, as the population became more literate, knowledge increased and revolutionary ideas spread outside the control of the church (who were basically the sole keepers of the written word during the middle ages).
Throughout the Renaissance (late 1400's to 1600's), there was an increase in literacy and the quality of life, and this manifested in the political and scientific revolutions of the Enlightenment (the 1700's). to cause the true end of Feudalism.
edit: it gets much more complicated than this, but these are the basics.