That's weird. Constantinople fell in 1453, long time before the current Greek state was created. Before 1923 and even after (until some 'pogroms' in the 50s) there was a sizable Greek minority in that city, but it has had a Turkish majority for centuries. Nowadays there are about 2 thousand Greeks living there and the population of Istanbul exceeds 12 million. On the other hand, the outcome of the Greek-Turkish war is a clear example of how irredentist dreams usually end in nightmare. In other words, the imprudence of Greek nationalists ended in a bloodbath and with the deportation of their compatriots from Western Anatolia. Look at the former Yugoslavia: Serbian irredentists ultimately achieved that the Krajina was cleaned up of Serbians.
I, actually, met an Istanbul Greek guy this year (and not even in Istanbul, but in the US). It was almost as staggering, as if I met a live Neanderthal. Or a dodo.