I've always wondered if Yugoslavia could have survived had it actually started to collapse sooner.
Think about it...
Tito died in 1980 and the slow decline of the federal government starts. In OTL it didn't really come into play until 1989 when Slobo geve his infamous "None shall beat you again" speech in Kosovo. by then the Soviet Union was already on its last leg and had pulled out of most of Eastern Europe. But what if someone gave a speech like that several years earlier.
Let's say in 1985 an ambitious Serbian or Croatian politician pulls a "Kosovo Polje" type speech that rocks the central government.
Let's say this politician is Serbian. He starts calling for "democracy" in Yugoslavia. Thing is, to him democracy means "one man, one vote" and an end to the ethnic republics that the communists "shoved down everyone's throats" after WW2. He also calls for religious freedom and is very vocal in his Orthodox faith.
What is interesting in this scenario is that if this politician survives in 1985 without getting removed from office or arrested, he could single handedly turn Yugoslavia into another Angola. A cold war battlefield. The West had very little understanding of the underlying ethnic makeup (and tensions) in Yugoslavia in the 1980s (and even in the 1990s unfortunatly) so I could see the US suddenly coming out in strong support of this Serb nationalist who wraps his nationalist rhetoric with keywords like "democracy" and "an end to the communist dictatorship". If a civil war breaks out in 1985 it is likely that the USSR would not want to get involved directly (they were already trying to pull out of Eastern Europe). They probably would support one side with foreign and military aid however. The Americans would then support the other side (in this instance the Serbs). The Serb nationalist then "sieze" the central government in Serbia, take over the Yugoslav military, and then move on the other republics to "spread democracy". The Americans never look at it as anything more than "democracy versus communism" and continue to support the Serbs who eventually overrun the rest of the country. They end the federation, declaring the "Republic of Yugoslavia". After the fall of communism in the USSR in 1991 Yugoslavia is able to survive as a unified nation. A nation with serious ethnic strife, but it survives nonetheless.
Clearly a lot has to go right/wrong for this to happen. I really don't know if Yugoslavia could ever supress Slovenia if a war broke out. But I still could see that scenario possibly playing out if everything fell into place.