I tend to believe that Stalin would eventually make his mover westward, but not earlier than 1944. The geopolitical buildup of the world at that time (with the "capitalist" side fragmented and at war with each other, and with the Germans having sweeped over Europe) was favoring an USSR invasion, but they lacked the sheer power to do so (especially in the offensive - the lessons taken by the Soviet-Finnish war were quite fresh too). He knew though all too well that the tenderness with Germany could not last forever - and that he would've eventually to face them. But he didn't expect that before 1943 at worst - and that's why Barbarossa caught him completely off guard.
Stalin was preparing an aggressive for the somewhat distant future but I seriously doubt he would've gone as far as taking "the whole of Europe". I assume he would aim for the countries he got post WW too (eastern Europe) and perhaps a little more.
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