The question is: Would the meaning of Republican change, or would the meaning of communist change?
Given that the notion of communism implies a given set of requirements for the label to be appropriate, it seems to me that the meaning of "Republican" would change. If communists embrace a socially conservative, capitalist approach to policy, they are no longer communists by any means of the word, because to be communist implies certain innate beliefs. However, "Republican" is just a name: from Lincoln to Eisenhower to W. Bush, the Republican Party has always been the Republican Party, even if those who represent it are completely different from one another.
Stalin wasn't a true communist, but that doesn't stop everyone from calling him a communist.
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