There are Soviet armies in Anatolia
Come a Greek- Soviet war they can march into Ionia or the asiatic part of the straits. Why are you all assuming that if Greece goes renegade Stalin is going to take the slap belly up?
Because this is not a video game!
Honestly, first there has to be a Greek-Soviet war. By the 1944-45 situation, IMO this is definitely impossible!
In 1946 it would be really hard for the Soviets to attack, because:
1st, they will be pretty occupied in launching a series of coup d' etat in Eastern and Central Europe and attacking Greece either through Romania and (50-50, remember?) Bulgaria, or Turkey, wouldn't be easy nor would help them in turning half Europe Communist.
2nd they still would be missing the necessary navy for launching such an attack.
3rd, regardless of what many think, I doubt that Stalin would risk dragging his country to another great war, without some time first to recover (both psychologically and regarding resources, infrastructure and population) after the devastating WWII, and definitely before consolidating his gains in Eastern and Central Europe. Because if the USSR launches a direct attack on Greece (even a renegate Greexe), through other countries with at keast some western influence, will definitely mean that the USA and the UK get involved.
Any Soviet move after 1947 is completely out of question!
So, IMO, any military action of the Soviets against Greece is ruled out, IF Greece is going to make a move on Constantinople.
So far, it seems that the up to now successful Greek political system is choosing the road of being discredited by the Greek public without any obvious danger, or collateral gain.
Remember that IOTL, in the mid-1950s Greece chose to stand and make a case against Britain, and even send a guerilla force against the British in Cyprus. And maybe Britain at the time was a trembling empire, but still an empire and No 2 in the NATO, while Greece was a devastated bybthe war country, one of the poorest in Europe, politically torn by a civil war, corrupt, with a still hungry population depending on foreign aid, with an unstable political system, a weak army, already in the Cold War, etc.
What Greece would risk IMO is a degree of political alienation, but one far from that of OTL 1920, due to the Greek contribution in the war effort and the publicity this contribution had in the western Press.
To close my arguments, I expect Lascaris to have a hidden card to show us, as I doubt things can plausibly develop as they seem, at least without a big damage to the Greek political stability and the Western prestige (Churchill, especially) in the last stages of the war and after.