Let's say the Ottomans stay neutral in the First World War or something, or perhaps even lean slightly into the pro-Allied camp: enough to retain their 1914 borders, but not enough to grab anything else. How do the Greeks, Armenians, Kurds etc fare?
I wonder what would happen to a surviving Ottoman Empire when decolonization comes around (if it does). Especially considering how much oil the Ottoman Empire will turn out to control, it will be a major player in global politics, and it could easily turn out to be in some power bloc's interest to promote nationalist (especially Arab nationalist) movements in order to destabilize the OE and harm whichever power bloc is its major trading partner if/when there's a re-match of the alt-WWI.
I guess they would be treated quite well. Local autonomy and the ability to have government documents written in their languages. Turkey seems to have a good thing going with its minorities, I assume the Ottomans would be the same thing.
While ethnic nationalism was a problem in the late Empire, there was a parallel current of thought that opposed it: Ottomanism, the idea of a cosmopolitan transcendental national identity. This outlook actually had quite a bit of popularity, especially in the middle class and some peasantry, as most of them didn't really have a conception of nationality to begin with. Of course, this worldview disintegrated during the war, but if that's avoided, and the government pushes it, it may well cancel out most of the nationalist rhetoric. The Empire can then use its newly found oil money to buy off the few remainders.
Now this might provide an avenue for Arab nationalism to develop- specifically a movement denying the legitimacy of Ottoman Caliphate based in part on it not being "fundamentalist" enough and in part on it's not being Arabic enough(little basis in truly fundamental Islam for the latter sentiment hence the quotation marks, but their is a substantial strain of arrogance and chauvinism amongst Arabs based on the idea of being Islam's foremost standard bearers, and an especially liberal caliph might antagonize that). It's unlikely to form a majority amongst Arabs, but it could cause the Ottomans no shortage of trouble in terms of terrorism.Another thing-Islam would be a lot more liberal today than IOTL.