If those maps are based on a POD in 1920 as you mentioned, then they really aren't very applicable to this timeline's situation. The POD was a century earlier. While there's no POD that can win you the napoleonic wars(or equivalent) for France in 1815, there's plenty in 1715. Same here, starting in the 1920s, there's no good way for Greece to own Constantinople or the entirety of the straights zone.
With our POD in 1820, and the way the timeline is headed, Constantinople is near guaranteed, and the straight zone along with the whole ionian coast is likely in my opinion. If the turks keep getting smashed by the Russians, their demographics hurt by many wars centered on their muslim populations, while the christians of the empire are more prosperous, then by the 1920s you get a different situation. Instead of Armenia and Greece being worried about being able to hold on to what they have from the vengeful turks, you can have the opposite situation, of Turkey struggling to defend their lands from Armenian/Georgian, and Greek incursion.
While the Turks certainly had the demographic advantage at the time of the POD,1820, a lot can change. A century ago Germany had many times the population of turkey, almost 10x, today there are more turks than germans. A series of disastrous wars, financial collapse, and bad governing can seriously hamper a population, while good government and successful expansion leads to large populations during this time period. The greeks and caucasian christians got shafted really really hard in OTL. While I wouldn't wish the same fate on the turks, it's not an impossibility.