That's a good idea, but the question is what nation can form/restore Bulgaria? Byzantium/Rome, highly doubtful. They're not of South Slavic cultur. Serbia? Even though Serbs and Bulgars are similar, it feels unnatural for Serbia to form/restore Bulgaria. Bosnia is the same and Croatia is under PU with Hungary. Also if we take religion into account and say that only Orthodox South Slavic nation can make such decision this would mean that both Bosnia and Croatia need to switch their religion. I think that independent Bulgar minor tag(s) should exist, like Karabakh for Armenia. Now this is only my opinion.