What if the Greek Junta doesn't collapse, and instead wages a war against Turkey over Cyprus?
It all depends on when they decide to go for war.
In OTL there were considerable forces there, that would inflict very heavy losses to the invasion fleet if they were deployed in time.
I am sorry, but you are wrong.There were not considerable forces there, and it was the Turkish intervention that caused the Junta to collapse.
If they had decided to go to war with Turkey, I don't see how they could have accomplished much, given the relative distances of Turkey and Greece from Cyprus.
Why shouldn't it happen?If that happen, Greece would have to leave NATO, and perhaps start to lean on their ideological nemesis in Moscow. A war between Greece and Turkey would be a worst case scenario for the US. Suddenly Makarios would not quite be seen as the Castro of the Mediterranean anymore.
It was in the best interest of the US to have Greece and Turkey not go to war, but I read theories that the whole Cyprus crisis was in the best interest of the US. It got rid of the Greek junta (that was a huge embarassment for democratic NATO) and it taught the Greek Cypriots that it was dangerous to flirt with the Communists. So all in all, the winner in Cyprus was the US. If Greece and Turkey had gone to war, then the big loser would be the US since they just lost Greece as a Mediterranean ally.