What I find interesting are the ramifications in Yugoslavia. So far we know the following:
- The Chetniks were strong-armed by the Royal Yugoslav goverment to become active against the Axis.
- The Royalists have a battle-hardened and mostly serbian field army in Greece.
The Royalists have significantly greater legitimacy compared to OTL. Along with this legitimacy the Chetniks will have a sginificantly greater arms supply by the Allies. The royal goverment has enough significance (read: a small field army) to persuade the British to minimize the supply to Tito.
I think the stage is set for a post-war Yugoslav Civil War. It will be brutal. I don't think that any side will have an overwhelming advantage. If I may make a guess, I think it is possible to see Yugoslavia splitting in three, between a royalist Serbia, a communist Croatia and a liberal Slovenia. The map I have in mind is this one with the border depicting the pre-war Banovina of Croatia.
Under these conditions, Italy might retain Istria. Tito will have much bigger fish to fry in Bosnia and Krajina. If Italy manages to be more useful to the Allies than OTL, then the chances for an italian Istria are maximized.