So, assume Stalin is a bit more deceptive. He still negotiates an invasion of Poland with Hitler, and when Germany executes the plan, he also invades. However, when both german and soviet forces meet, Stalin declares war on Germany and attempts to invade the country.
-How much of a chance do the reds have to defeat Germany? I reckon that their selling of armaments to the germans at a cheap price for the duration of the Molotov-Ribbentrop pact really helped the execution of Operation Barbarossa. In retrospect, does Stalin deciding to not purge some of his more competent generals in the 1930's help the invasion?
-How do the western powers (Britian, France, and others, possibly the US) react to this? Will they concur since Hitler was harassing the western european powers good time in the 1930's or will they look at it with suspicion, like as part of a soviet plan of dominating eastern Europe and acquiring a springboard for inciting a revolution in what's left of Europe?
-How does this affect the Winter War? Will the soviets be forced to retreat in order to not piss off the western powers more?
-In case and after Germany is defeated, what will the new political scenario in Europe look like?