Ok, I got this weird thought in my head this morning. Assuming a) Neutral/Nonbelligerent Italy
Apologies - I didn't notice this bit!
How goes the war without Italy? Well, Germany still has a great defence on its Southern flank, probably even better than OTL since Italy is neutral and not about to be invaded...
If we can assume that the fact that there are no huge setbacks in Africa (as there were through Italy's entry into the war) then its POSSIBLE that Italian neutrality would not end up with an invasion of Greece, as there's no huge loss of face to overcome. On the other hand, with the rest of the world involved in a war, Mussolini might see it as an ideal time to have a go at Greece...
But we can assume he doesn't. Maybe the British are secretly offering him concessions to remain neutral, he would certainly have that card to play (especially as they don't know how much of his armed forces are more show than reality)
Bulgaria is more complex since Hitler is still going to want to smash Russia. Presumably he can reasonably trust Mussolini not to do anything treacherous, so he can make preparations unencumbered by either Libya or Greece, and thus probably not having to intervene in Yugoslavia either
But that doesn't stop the growth of the Axis as a weapon against the USSR but if Yugoslavia manage to maintain a pro-Axis neutrality, I agree it is possible that Bulgaria may also do so - they will certainly gain nothing from engagement in the war with Greece and Yugoslavia remaining neutral, not unless Germany forces Rumania to give them the Dobruja as per OTL but even then they may manage to be in the Axis but non-belligerent. I still think they would be pro-ennough to act as defence on the flank tho
But you MAY be right that this allows Turkey to decide to let an armada pass through the Straits but that is one helluva pro-Allied gamble.
And the Allies are going to be seriously worried about Italy - Italian neutrality doesn't mean they won't suddenly enter the war and destroy their supply lines. IMHO they will have to offer Italy Tunisia and a large part of Algeria at the least, and maybe Tchad and part of the Soudan. AND probably have to go public with this.
All most curious!
Best Regards
Grey Wolf