The black death helped to finish off the feudal system. Overnight there was a severe labor shortage, and peasants had mobility. Towns (free from enfeoffment) welcomed new workers, and even nobility would take migrant peasants offering better conditions because they were desperate for labor, as land with no workers had no value - could not even be sold to raise cash. Once peasants were no longer bound to the land, and mobility became established, feudalism was on the way out. If England does not have this die off (actually several waves of plague), then you may see feudalism last longer which will be a bad thing for England as they will not have an edge when mercantilism hits.