The tensions on the Balkans aren’t only due to the current ethnic makeup of the different regions, but also (or mostly?) because of history and politics. Kosovo might be populated predominantly by Albanians, but that doesn’t really stop the Serbian claims on it, as Kosovo has a deep historical and spiritual significance to the Serbian people. Not to mention redrawing of borders based on current ethnic composition (or any redrawing of borders, for that matter) would mean further destabilization of the region – f.e. this would also affect the Albanian secessionists in Macedonia, which could in turn be easily used by Russia and Turkey for their own imperial ambitions, both on the Balkans and elsewhere.
The key to stability on the Balkans is a joint and (most importantly) voluntary membership in a bigger union, be it the EU, the Intermarium or something else.