If the Ottoman Empire survived WWI, it could find itself under threat from the Soviet Union. The Ottoman Empire is a multi-ethnic state, and many of those ethnicities have exploitable grievances, the Soviet Union, with its position surrounding the Empire could destroy the Empire if it desired. In OTL, Turkey was relatively small and neutral, a surviving Ottoman Empire would be more threatening to the Soviets.
What Soviet Union is that? Open straits means a more credible Russian war effort. No Gallipoli, Iraq, or Sinai probably means a substantial Anglo-French force in Serbia by 1915. And that all probably means Austria is stretched to the limit by '16. Ottoman neutrality is highly likely to result in Entente victory and no Bolshevik Revolution.
If for some reason a Russian Civil War
does break out, the Ottomans will obviously intervene. They'll occupy Kars and Batum in about three seconds, and then keep going. The Azeris will certainly help them, and the Armenians may be that sensible too. Daghestan and the Mountaineers would be keen on Ottoman protection, hell, maybe even a Crimean Tartar state! And from Baku, Central Asia is accesible and the Ottomans can stir up plenty of trouble.
And even assuming a Soviet Union, and one which the Ottomans inexplicably decide not to intervene in to establish a healthy buffer zone, the other powers will never accept Soviet adventurism against the Ottomans.
The Soviet Union does not surround the Ottomans by any stretch of the imagination.
What nationalities have exploitable grievances? If anything, even the Dashnaks are probably going to conciliate in the reform-packaged Ottoman Empire and concentrate their activities in Russian Armenia... unless of course the intervention I outlined creates an autonomous Ottoman Armenia with its capital at Yerevan. And I simply cannot think of anyone with any exploitable grievances save the Armenians.
I agree that left to its own devices, the Ottoman Empire could continue for quite a while. But even after WWI there are plenty of external enemies that may chose to tear the Empire apart.
Because of course contrary to all the evidence of WW1 the Ottomans are utterly incapable of self-defence.