I don't know if it becomes a retronym (although that's what it should be called "protomarxism.") It is the initial theory of Carlos Marx, oriented more to philosophy than the later one, clearly political and sociological. This name "new Marxism" began to become popular after the fall of the Soviet Union, as traditional Marxism is closely associated with communism as a political system and not so much to theory. See neo- prefix ( "new" ) .
