Alternate history is fun.
Remember, Hitler's rise to power did not happen in a vacuum. Events in the Pacific were proceeding unaffected by what happened in Europe. The U.S. and Japan would most likely still have gone to war, and the U.S. would still come out as top dog. The cold war would have looked quite different. Whether or not this would have been for the better or the worse is another matter.
Germany was under pressure from domestic Communists. However, the Weimar republic was in better shape in the 1930s than it was in the 1920s (still doesn't say much). Franco was also getting aid from Italy. France was a wreck, and was paralyzed by the different political factions.
Many options exist. It would have been a mess regardless. If Germany falls to a Communist revolution, most of Europe would probably follow. Germany was an important buffer for France and the only stabilizing influence to it's neighbors in Central Europe, even weakened as it was. If Germany stands, the Soviets might have attacked sooner or later, but would be forced to go through Poland on the way. Poland had defense treaties with Britain and France, and it's doubtful Germany would stand still while the USSR attempted to take over a neighbor.
Another factor to consider. The Red Army flat out SUCKED in the 30s and 40s. Read about the Winter War with Finland. Poland also defeated the Soviet army in a short war in the 1920s.
Italy was also fascist by this point, and Mussolini was generally being a pain in the ass to everyone. The Balkans were insignificant, and have been since the breakup of the Austro-Hungarian empire.
To summarize:
Britain as a strong anti-communist influence on one side of the continent. It is capable of projecting power into the Balkans through Greece. France significantly weakened militarily, but fairly strong politically and certain to survive and follow Britain as long as a sort of buffer was maintained.
Germany as the only possible anti-communist influence in Central Europe. If Germany goes Communist, the Allies lose all ability to project any sort of power into Central Europe, and France loses it's buffer, severely weakening it and exposing it to Communist revolution.
The Soviet Union has the ability to project power into Central Europe and the Balkans, but only at the cost of drawing Britain and France, and probably Germany, assuming it remains non-Communist, into war (not 100% certain in the Balkans).
Italy is a wild-card. It can't do much militarily, and Mussolini was probably too cowardly to try without Hitler to save him. However, it can beat on small countries, screw up attempts to form coalitions, and generally be a pain in the ass to everyone involved.