I don’t believe sepperate states could solve the problems. In fact, these can make it even worse. I think it would be better if all ethnic groups were still under one leader and got some sort of autonomy (like culture, education). Don’t want to boast, but the Belgian model could have been introduced in Yugoslavia I think without having a civil war. Maybe you could claim the state was artificial, but be it so, if that could avoid thousands of human lifes.