Hitler wanted Lebensraum ('living space') but to do that he does not need Moscow. The area on the Western Russia and Ukraine would do it.
So let us say that everything happens the same as the OTL except that when Hitler here launches Barbarossa he claims it is to enforce the Treaty of Brest-Litovsk.
Hitler repeatably offers a peace treaty that offers in exchange for much of Western Russia, the communist and Stalin regime survive, they can keep the Eastern area. As time gets on particularly once the Ukraine falls, too many in Russia and Germany, Stalin would appear to be offering nothing more then he has already lost to make peace and save his regime.
Will the government of the USSR accept this German peace treaty?