1914 borders, plus Soviet Galicia, are the most likely short-term outcome here in terms of what the map looks like. The only question is whether the Soviets create a Polish SSR or instead form a puppet state.
Diplomatically, as noted, the British and French are liable to lighten, if not toss out altogether, many of the Versailles restrictions on Germany. Whether this is enough to assuage German concerns enough to prevent the rise of the Nazis or some other form of German revanchist movement that is just as anti-western as it is anti-communism is also a open question.
Additional communist revolutions are unlikely and the ones that did occur are only marginally more likely to succeed. The Soviets may toss them additional armaments, but are unlikely to go as far as all-out war to try and aid them. The failure of these revolutions are likely to still dampen enthusiasm among the Soviet leadership for Permanent Revolution, although maybe not quite to the same degree as OTL.
Poland’s fall does mean the Soviets are in a better position to grab other parts of the old empire that got away from them OTL: the Baltic’s and Finland. How the inclusion of them and a Sovietized Poland (whether nominally independent or absorbed as an SSR) would affect subsequent domestic Soviet politics is anyone’s guess.
Let me reiterate that the above is merely what I regard as the most likely outcome. Most other scenarios advanced here I do not regard as impossible, merely less likely./quote]