Kemal is killed during the war, and the Greeks don't go nuts and over-extend so that they have a more reasonable and defensible chunk of Anatolia. Because of the crisis, the Entente powers (minus Russia) declare Constantinople an international zone, Greece having the western border of the zone, the Turks the eastern one and for 10 km each side the area is demilitarized. Greece gets all the Aegean Islands that would be Turkish OTL (Italy still has its few).
You have a rump Turkey, you may see a Kurdistan across parts of OTL Turkey, Syria, and Iraq perhaps with a small chunk connecting to the Med. An independent Armenia with some expansion in to adjacent Turkey might happen, but the entente won't let a Soviet Armenia do that.
That's the geography. The demography will be ugly. Any Turks in now Greek territory will probably leave (vertically or horizontally), and likewise Greeks or other Christians in the Turkish zone. A Kurdistan will probably be relatively tolerant of minorities like Yazidi, Christians (of all sorts) and Jews. The process of sorting out the ethnic lines will be quite as ugly as anything that went on OTL. Constantinople will reamin multi ethnic in the international zone, you might see the Hagia Sophia back as a church not a mosque.