Well, depends on POD. I think best way would be for yugoslav partisans to be less successful, needing greater soviet help. With that Tito has less of a free hand after the war (let's ignore the butterflies greater soviet focus in Balakns would mean for German front).
Or there is no disagreement over Greece, more likely Tito doesn't back communists that Stalin doing it. Albania might be absorbed, not sure about Bolgaria.
Anyway, if Yugoslavia joins WarPac SU gains warms sea port outside Black Sea which is connected to it via land route. Greater militarization of NATO southern flank (Italy, Greece) and greater US, British and/or French presence there (thoughlikely limited to US only). Maybe greater effort to keep tensions between Greece and Turkey to minimum as to not disrupt things. Greater soviet naval presence in Med (would have effect on Arab-Israeli conflict). Maybe Egypt allows SU naval basing potentially butterflying 1956 war or making it very different?
After the fall of communism things get interesting. if Albania is absorbed Albanians may want more rights or outright independance, assuming Kosovo and Albania are merged into one unit/republic. As far as Slavs are concerned, maybe hated/resented soviet presence is seen as a unifier, making them common enemy. Once they are gone Yugoslavia either breaks up smoothly (CSSR style) or is transformed into looser federation.