turkey is a bizarre country, because it is a historical power that is universally viewed as an occupier. it has historical power over this broad swath of land, but no historical connection to any of it. none of these areas ever really became turkish, but the turks never really assimilated to the area, either. and, all of these fragmented states around the old byzantine empire, including those that converted to islam, are united only in their opposition to turkish imperialism.
i've written this essay a few times, now. as these economic blocks build up around them, the turks are kind of at the end of their history - they can neither enter into a block, nor can they take control of one, as their geography and history would demand of them. the turks seem destined for some kind of catastrophe, one way or another.
there is an argument that the turks ought to join the eu, as the region has a deep history in europe. this would be a reunification of the empire, in some sense. but, the europeans do not seem to want them in europe, not any more than they did five hundred years ago. there is no doubt some subconscious feeling that the turks will eventually fall, that constantinople will be liberated, but the way that works itself out in actual policy is a kind of distant tolerance that never reaches acceptance. yes, the turks exist. c'est la vie.
there is likewise an argument that the turks ought to join the arab world, but the history here is truly no less hostile - the arabs never conquered the city, but were rather conquered by it in what was really a muslim phase of roman imperialism. whatever role that christian theology played in the egyptian and levantine revolts of late antiquity, it is clear enough that the arabs were eventually welcomed as liberators to end what was a long roman-persian war that had been fought on semitic lands for a thousand years. turkish expansion via the sultanate of rum (after the mongol destruction) was in a real sense the return of the romans from the inside out; in the end, it was more like a long civil war that ended with the muslim faith dominant, and the old regime back in place. and, if it weren't for the inability to convert the greeks, that turnover may have been historically total. as it is, the collapse of the ottoman state was also the most recent liberation of arabs from roman hegemony. whatever historical process exists around this in the long run, one should expect the arabs to give the turks the cold shoulder into perpetuity.
i would suggest there is a far better argument to unite istanbul with moscow, and resurrect the byzantine state. but, the peculiarity of the turkish state asserts itself once again, here: while greeks and slavs are forever historically intertwined, the fact that the turks are muslims is a difficult cultural block in reunifying the east. that said, the future of the region is no doubt in secularism, rather than in islam or christianity. and, for that reason, a new eastern empire rooted in universal secular values is perhaps the most historically correct home for turkey, in the end.
the other option is for turkey to look directly east and try and project some kind of dominance over the turkish areas of central asia. while this may seem rational to a naive observer, there is no history of a unified turkish state, and certainly no history of a turkish state centred in the bosphorus. rather, the idea being projected is of iran - this is the iranian cultural sphere, the iranian empire. and, while the geographic space we call turkey has historically existed within iranian empires, it has never been assimilated within one. there is a line through the peninsula, on the western side of which the idea ceases to make any sense.
the war in syria has maybe made the problem of turkish isolation more obvious, but it hasn't presented any meaningful solution. europe is as hostile as ever, as they carry out a proxy war against the arabs and continue this awkward frenemy dance with the iranians. but, that russo-turkish alliance is potentially the basis for a deep friendship and potential economic integration - whether the current turkish leadership realizes it or not.
for right now, the russians need to be careful not to let them occupy syria, as that's just going to set the whole thing back in motion again.