In my opinion it was a major mistake by Tito wto keep the capital in Belgrade. The city is in the center of Serbia but was far from the other Yugoslav republics. As a consequence the city stayed Serb instead of becoming a reflection of the diversity of Yugoslavia. This made it much easier for the other republics to secede as they saw Yugoslavia as the state of the Serbs. Just imagine how different it would have been if the capital had been moved to (for example) Tuzla. Would the Croats have thought just as easily about seceding when the capital had contained as much Croats as Serbs (for example 300,000)?
This is how the Swiss do it: the capital Bern is in the German speaking part (two thirds of the population speaks German). But it is very close to the French-speaking part. Together these two groups are more than 90% of the population.
I mention this because Bosnia and Kosovo are in a similar position. Both follow policies that have resulted in ethnically clean capitals - although Sarajevo still has some Serbs - and with that given up the idea that they are multi-ethnic states.
Yet the "international community" keeps up the appearance they are multi-ethnic. I think they should pay more attention to the attributes of multi-ethnicity. Either they should work on them or they should give up on their illusion.