Here is a map of the population of the Ottoman Balkans I painstakingly assembled, which I think is pretty interesting, and opens a lot of AH channels as well.
A few striking points:
1. Muslims were a majority or at least a plurality in a surprising proportion of the Balkans - the only place where they are not a strong presence is the Aegean Islands. On the continent there are only three provinces where they are not a majority/plurality: Sofya, Manastir, and Yanya. They constitute approximately 43% of the total population.
2. Bulgaria was put in the wrong place. Large swaths of it contained very few Bulgars at all, necessitating the ethnic cleansing of huge numbers of Muslims, and the Bulgars of Macedonia were left out of the Bulgarian state.
3. The position of the Muslim population probably goes a long way to explain the resilience and longevity of the empire - the border regions tended to be heavily Muslim.
4. The Muslim area of the Tuna province (today's northern Bulgaria) was principally Turkish, with a large number of Tatars and Circassians, the latter two constituting about a third of the Muslim population. Much of the Turkic element actually preceded the Ottoman period and had lived in the area as long as the Bulgars had.
5. Muslims were nearly a majority in Bosnia, which included Novi Pazar. There were overwhelmingly converted Serbo-Croats. Much of the area colored "Greek" is actually Albanian and Vlach Orthodox - that is why it is difficult to determine which is the largest group in Manastir - and the Greek majority in Yanya is considerably smaller than you might think, if it is a majority at all.
6. There is more detail for Bosnia and Bulgaria because these provinces were investigated before the Russo-Ottoman War. Figures from the census of 1881 are good, but by then the remaining territories of the empire were much more heavily Muslim, so it's only possible to determine the overall Muslim percentage of the population for the province as a whole, except Iskodra, where no refugees went.
7. Language ran in a continuum, running roughly West to East, beginning as Serbo-Croatian and drifting into Bulgarian - it was not until after the creation of ethnic nationalist states that dialects were standardized. That is why the question of to whom Macedonia "belonged" was so tricky. Obviously though, Greek, Albanian, and Turkish were totally separate languages.
8. The category "Greek" is tricky because in censuses this included all Orthodox Christians until the creation of the Bulgarian Exarchate. The Patriarchate attempted to Hellenize as much of the Slavic and Albanian population as possible in pursuit of the Megali Idea. They had some success.
The scale of the human tragedy experienced by the Balkan Muslims is also pretty clear. To spell it out:
Bulgaria - 1M refugees, of which half died, and 300K massacred.
Serbia - 100,000 massacred (the Nish subprovince)
Greece - 50,000 refugees
Bosnia - 100,000 refugees, 250,000 massacred.
That's 650,000 refugees and 1,150,000 dead. This is also almost certainly an understatement, due to undercounting, and because all the Circassian and Crimean refugees living in the Balkans had also to be withdrawn, and numbered at least 500,000. I don't know how many Muslims were liquidated in areas taken over by Montenegro, but it's significant.
The best statistics available in the post-Berlin period are not surprisingly the Austrian census data for Bosnia. There we see the tell-tale drop off in the number of young males which is characteristic of ethnic cleansing, and continued long into the Hapsburg period. The Muslim birthrate also plummeted.
The influx of refugees and the continuing stream of Muslim immigrants from the Balkan states had a drastic impact on the ethnic balance of the territories remaining to the empire. By the turn of the 20th c, only Yanya did not have a Muslim majority or comfortable plurality.
The Balkan Wars resulted in an even greater loss of life, followed by WWI which topped even that. This is the primary reason why modern Turkey is so paranoid about separatism - it has inevitably been accompanied by genocide on a Hitlerian scale.
Anyway, with regard to AH possibilities, the following spring to mind:
1. The loss of the Balkans is not inevitable. If the Ottomans can stay out of wars with Great Powers, the population balance is likely to increasingly tilt Muslim as rail lines are built and people move from poorer areas to the more developed regions of the Balkans.
2. There seems to be to be a great likelihood that if Bulgaria had achieved statehood under more "normal" circumstances (i.e. through gradual increases of autonomy as experienced by Serbia and Rumania), it would have been located further West.
3. If Bulgaria does gain independence, the Ottoman position in Albania and Bosnia is untenable. However, it does seem quite possible that the Ottomans would be able to retain a large swath in the Balkans covering the Eastern half of today's Bulgaria and stretching to Salonika.
4. Due to the language issue in point 7 above, the creation of a large South Slav state is conceivable. Serbia is the fulcrum, and is the obvious focal point for it.
in Bosnia...
