I am curious, seeing all this conflict to this day in former Yugoslavia between South Slavs:
What would be long-lasting solution that would please all sides and keep yanks out of Balkans?

Honestly, the U.S. supported ethnical separatism in Yugoslavia, state building along ethnic/religious lines, Yugoslavs (Serbs to be precise) were against it. Now when the Americans started with the job, they should eventually end it, without bloodspill however through a compromise of the states involved, since it is more than obvious that people that were at war with each other are not the ones that can build a functional government together, since their ideas differ 'a lot' (well they differ to the point of war.)

Unfortunately they left the job undone, frozing the war without settling it. The conflict is not over, it is just frozen and under foreign administration, to stop further humanitarian disaster. The conflict will end, when they make the job done of dividing everything by ethnic lines, this time supervised by them under a clear compromise of all ethnicities involved.