I have to disagree with you on this one Mitch. As you rightly assert, the loss of Malta would have been a terrible blow, but I think it would have been a fatal blow for the Allies. If Germany takes Malta, it controls airfields on both sides of its supply route to North Africa (Malta and Sicily). Regardless of British control of Gibraltar, and the strength of the British fleet the Axis, not the British, would control the Mediteranean from these two unsinkable aircraft carriers (we all know that absent control of the air, a fleet is merely a target).
With control of the air and the supply route, and a focus on North Africa rather than Russia, no offense to the brave men of the 8th Army, but they wouldn't have stood a chance. They would have been cut off from supplies, and facing 100% of the German effort, rather than less than 10%. The Germans would have taken the Suez Canal, pushed on into the Middle East, and secured the oil fields. With this unlimited supply of oil, even if the British didn't surrender, the Germans would then have been able to focus 100% of their efforts on Britain alone. If they figured out that attacking the airfields was the way to go, they would have obtained air supremecy over the English Channel, and prevented British warships from protecting the coast. Eventually, they would have been able to force a landing, and win the war. In the alternative, they would have had time to focus on the U-Boat war in the North Atlantic, and starve the British into submission. Either way, the loss of Malta, and the subsequent inevitable loss of the Middle East, would have ensured British defeat.
For my money, the Nazi attack on Russia, and the failure to appreciate the need to take Malta, were the two biggest keys in ensuring their defeat. The brave defenders of Malta get no where near the credit they deserve. They, and the Russian troops who held at Stalingrad and outside Moscow, saved the free world.