On the other hand, I doubt anti-Hitlerian (Soviet-backed is probably what you want for this scenario) coup in Germany against Hitler would consider continuing the Holocaust; it would be seen as a waste of resources, though official discrimination could -- probably would -- well continue.
The Holocaust was only commenced when the Soviet Union was invaded, and pursued systematically after war was declared on the USA. As ironic as it may sound, Germany relied on Jewish investment houses in the USA to finance its army. German Jews served as hostages, and the Jewish investment bankers in New York were led to believe that, by brokering loans to Germany, they could protect their German brethren. Key players in this "game" were the Warburg cousins, Felix Warburg as CEO of Kuhn, Loeb & Co, (later merged with Lehman Brothers) and Max Warburg, head of the original Warburg bank in Hamburg, and board member of the Reichsbank until 1938. Accordingly, until war was declared on the USA, German Jews, while heavily discriminated socially and professionally, were not physically endangered.
The invasion of the USSR provided a 'testing ground' for prosecution and extermination strategies that was largely hidden from the eyes of the German and international (American) public. Most German Jews were well integrated, had often fought in WW I, and, for their roles in business, law, medicine or education, possessed influential networks, which already made their discrimination, and even more so their (open) murder, politically risky for the Nazis. The Eastern European Jews, with their distinct culture and language, could much easier be presented as 'alien'.
As such, without invasion of the Soviet Union, the Holocaust would most likely not have taken place. There was close organisational and time-wise linkage between preparing for the invasion and for the killing of Eastern European Jews, which indicates that the Holocaust was among Hitler's motives for invading the USSR.
I furthermore don't think that a Stalin-backed coup against Hitler would have had chances of success. German Communists, whose prosecution started directly in 1933, lacked the manpower and organisational strength (which is why
Herbert Wehner, who in 1941 had been sent from exile in Moscow back to Germany to organise such a coup, decided it was better to get imprisoned in Sweden instead).
Resistance cells within the German army organised around old Prussian nobility, who were appalled by the Holocaust and German war practices on the eastern front, both of which they regarded as violation of military ethics and codes of conduct. Asides, they had realised after the Battle of Stalingrad that the war was lost, and, in the old Clausewitz school, wanted to finish it as fast as possible. In the absence of such motives, I doubt that they would even have listened to USSR agents trying to motivate them for a coup.
Hitler not invading the Soviet Union implies a different Hitler - more political realism, less anti-Semitic and anti-Slavonic fanaticism. Such a leader would, after the failed attempt to invade Britain, have realised the potential stalemate and tried to negotiate a peace deal with Great Britain. Such a deal depends, of course, on the offer. I could, e.g., imagine that in 1941, a return to the Pre WW I status quo would not have sounded too bad for Great Britain.
