Failure in Crete (assuming falls apart quickly) gives the Germans a little less than 3 months before Barbarossa to consider their options... Taking Malta at that point in early or even mid 1941 would actually be easier than Crete and the island was less well defended... attacking Turkey would have to be a massive operation, canceling Barbarossa (I would be of the opinion, you would need at least two infantry armies and a panzer army, plus significant air assets to beat them down)... barring a political collapse, it would take the Germans probably the entire summer to militarily smash Turkey and achieve their objectives, they could advance down the eastern shore of the med in a pincer move with Rommel (British resistance in this time of scenario could be overcome) the big question would be would Stalin see an attack on Turkey as an act of war against him...
I don't know how much credability the Luftwaffe would have after a failed crete... they lost the battle of Britain, and Crete was an entirely Luftwaffe operation (the fallschrimjaeger where under LW command)... I don't think Goering would get sacked (Hitler never fired him till the bitter end despite near total incompetance) but he could be seriously uninclined to listen to him anymore and seek other alternatives
Taking Malta would be easier than Creete, yeah, right.....
Written by someone who has never seen the island, I will lay odds.
Anyone who even contemplates landing on Malta by air is a certified lunatic - you cant land gliders, and even airdroping would lead to hude numbers of troop injuries. The place is basically a giant rock garden split into lots of little rock gardens by these big rock walls.....
Oh, and it also has serious defences around the only good place to land by sea, the harbour (rest of the island - basically vertical rock walls, with a few coves that dont really ead anywhere)