Literally impossible. The population is way too diverse. The best chance would probably be an Ottoman victory in the Balkan Wars and later decentralization leading to independence, but in that case the area would have a very substantial Muslim population, the eastern portion being Bulgarian Muslims and Turks, and the West containing Albanians; the south would have a lot of Greeks, the north some Serbs, and the capital itself would have a majority Jewish population.
It's hard to imagine it not being carved up by its neighbors.