It would be more like the USSR or "mainstream" Communist governments (not that they were all alike, Goulash communism and so on). It would also probably be a card-carrying Warsaw Pact member, which could have some interesting geopolitical consequences.
OTL's communist Yugoslavia had plenty of problems and dangers lying in wait. Just suppressing Serbian nationalism (or suppressing it more, since it was quite suppressed in OTL...) is not even close to the kind of comprehensive solution that was needed.
And yep, there's a distinct danger of civil war in Macedonia if/when the country breaks up. The Communists were very hostile to Serbian nationalism, but they weren't exactly kind to Bulgarian nationalism either; IIRC, they planned to shove a bunch of Bulgarians into an enlarged Macedonia, more or less against their will.