Sorry if this has been talked to death, but I did a search and I didn't see any threads discussing this.
In OTL, the German assault on Crete was an extremely close-run thing: the Naval Invasion was repelled by the RN and the Fallschimjaeger Units involved suffered such grievous losses that they were gutted as a fighting force, and the Germans never again attempted a large-scale paradrop operation. Looking over the history of the campaign there were numerous points where the Germans could have been repelled, and had they been prevented from capturing the airfields, the paratrooper units would likely have been cut off and forced to surrender after a few days?
So what if Crete had held? What would have been the effect of an unsinkable Allied aircraft carrier with the entire Balkans within its range? Would the Germans and Italians have attempted to reduce it with their own air power? Would Crete have been another Malta? What would be the effect on the North African campaign? Is there a chance the war could end any sooner?