What were the long term Greek plans for the war? Take the Albanian city of Vlorë and then bargain border adjustments from a favorable position? They knew that a prolonged war meant German involvement.
We are lucky enough to have Metaxas’ diary, so we know the answer.
There were three scenarios. All had the same prerequisite, after August 1940, when an Italian attack became almost inevitable: The participation of Britain as an ally
1. “The best scenario”: The Greek army takes Vlorë, with British reinforcements in men and materiel, but the British RAF remains south of Thessaloniki, so the Germans are not “provoked” to attack Greece. After Vlorë is secured, the Greek army holds its positions until the end of the war. This was mostly supported by the General Staff, and everyone knew it was too optimistic.
2. “The WW1 scenario”: Metaxas, in his meetings with the British Ambassador, British officers etc, stated repeateadly that if the Germans were to attack, he wanted from the British to open a new european front in the Balkans, like the Macedonian Front of WW1. He assured them that as long as the British provided the Greek army with the needed materiel, Greece would hold. Of course, the only possible way for a permanent Balkan Front like WW1, was for Britain to hugely commit herself to this cause, i.e. bring massive troops, tanks, air-force etc. As the Greeks ascertained, Britain in 1941 simply had not the capabilities for such a task…
3. “The realistic scenario”: It was the grimmest, but ultimately it was what happened in reality: Against a German invasion, without enough British assistance, the Greek Armed Forces would fight a last stand like Leonidas in Thermopylae, the country would be occupied, the government and the surviving armed forces would go in-exile to continue fighting, but the final Allied victory would ensure that Greece would be among the victors and gain Dodecanese Islands, Northern Epirus and maybe Cyprus (finally Dodecanese were granted to Greece in 1948).
P.S. For the scenario of a Balkan Front like WW1, Britain approached the governments of Yugoslavia and Turkey, but both of them refused to participate.