There's where the problem lies. Those factories won't come online for another year or two, and the transport systems to ferry resources from the former USSR regions to those factories will likely take even more time to build up. The surge in industrial output won't happen until '44 or '45 at the earliest.
Meanwhile, it's going to take just about all the manpower that the Germans can afford to field in order to pacify the occupied areas and maintain adequate levels of resource extraction and delivery, so the number of troops redeployed to the Atlantic coast may be a lot lower than you might expect. Granted, the experience levels of those troops who do return to the west will be higher, and some of the inexperienced reserves guarding the coasts might be sent to relieve veteran units, but the changes won't happen overnight. There's still a sizable window of vulnerability that the US/UK could exploit. It all comes down to whether or not the US public is willing to suffer the considerably higher Allied losses that a one-front war in Europe would entail.
On the other hand, with Stalin out of the picture, the Allied focus might return to taking out Italy and advancing through the Balkans, rather than going toe to toe against the Germans along a limited section of well defended and easily reinforced coastline. The Allies would likely have had the support of several groups in Yugoslavia who wanted the Germans gone at any cost, and the Hungarian government had already made overtures about a change of sides.
I don't see the rapid fall of the Soviet Union as a "war winner" for Germany, but it would very likely have dragged the conflict out for several more years, by the end of which the Reich would be a smoking radioactive wasteland.
The most vulnerable parts of the Southern Med. Coast (Spain, Italy, Greece, Yugoslavia) are all highly mountainous- thus easier for the defenders. Sure, landing is easy enough- but getting out? The Italian Campaign is a pretty good example of what happens. The Germans were doing pretty well in holding the line- they lost because of critical lack of supplies. Soviets Gone? Good luck with that land invasion of Europe. The Atlantic Wall is going to be as tougher than ever, and Southern Flank attacks are just going to end up like Italy or, worse, Gallipoli.
Air power is a more serious question. USSR GDP/Capita was always much lower than USA GDP/Capita, this, coupled with Soviet burn and retreat tactics, meant that not only would industry take years to recover,
Trying to force Hitler out via nuke is not going to work- unless you want to destroy the world while you're at it. Once nuclear winter starts to set in, good luck convincing the American population to stay motivated in war. Nukes in 1940 are immensely overrated.
Again, that's assuming it's not just another Italian Front. Tanks don't work well in mountains, and the Balkans were littered with them. Greece, with its narrow front, guarantees another Italian Front. Invading Albania from Allied Italy is better, but not by much. The Dinaric Alps form a 'wall' defending the interior, limiting entry into the interior by mountain passes.Hungary was pro-German primarily because it was either be eaten by Germany or by Russia, and Hungary had a lot more "issues" in the past with the Russians. Horthy, the Regent of Hungary at the time, was strongly opposed to Hitler, and the cabinet was heavily divided, but mostly trying to limit the damage rather than actively support Hitler. Overtures had been made covertly to the Allies early in the Soviet campaign, and which would probably have continued regardless of the outcome in the East if they hadn't been so thoroughly rebuffed by the UK, because ultimately there was no long-term safety with Hitler. There were still rumors circulating until practically the end of the war that US paratroopers would suddenly show up to assist against Germany. Former US Ambassador to Hungary J. F. Mongomery's book "Hungary, the Unwilling Satellite" goes into the political motivations and personal opinions of most of the leadership up until Hungary's formal entry into the war.
Tito's was only one of several factions in Yugoslavia opposed to the Nazis, and several groups were likely to suspend their feuds with each other until Hitler was out of the picture, if there was any hope of success. Hitler had very little actual support beyond his own troops, other than those he could manipulate through direct fear of reprisal.
Having the Allies push up into the Balkans would likely have galvanized support in those countries, and it was primarily on account of Stalin's expressed desire to keep the Allies out of the area that those plans were scrapped or never fleshed out in any detail. With Stalin out of the picture, those plans could have proceeded. Basically, the Balkan countries might not have been of all that much assistance, but they wouldn't have been fighting FOR Germany, and it would have spread Germany back out into a 2 front war, at least to a limited degree.
Invading Italy via Slovenia leaves a narrow coastal corridor around Trieste- a Axis with sufficient reserves could simply block the narrow corridor.
The Allies have an inherent disadvantage- their supply lines are coming from another continent, and Airplanes are no different.No.
America can make all the planes she wants; she has to transport them to Britain, keep them operational, the morale of her crews in check, and ensure the American People don't vote you out of office in 1944. There are plenty of profits to be made trading with Nazi Germany.
Operation Point Blank, mandated at Casablanca, is essentially ordered at the exact moment the other poster suggested Russia had fallen. Their stated primary targets are German aircraft factories.
In late 1943, months after Russia will have ceded the field, the Schweinfurt Raids prove that unescorted bombers will not be able to operate over Germany. If Russia falls, it would be called the Schwienfurt Massacre.
Germany is essentially fighting the Battle of Britain in reverse. You are fighting over German radar, German AAA, and German pilots will parachute to safety over Germany held territory.
Under this scenario, in addition to the extant problems the Allied air forces face, you just handed the Luftwaffe approximately 1,000 extra fighters manned by veteran pilots from the Eastern Front before the American effort even begins, not to mention large numbers of heavy caliber AAA reinforcing the German air defenses, all of which will make Allied losses completely unbearable. Plus, all future air assets will be prioritized for the West, not the East.
German fuel scarcity will no longer be an issue. Germany can put planes in the air and keep them there with a hard CAP over her industrial regions.
The layered escort system of the Allied air forces using P-51 does not come online until '44. By this time, Speer has racheted up fighter production from 5,000 in '42, to 10,000 in '43, to 25,000 in '44. Rather than producing 5,000 fighters in '45; Germany will be producing closer to 50,000 as her new factories and resources come online, lead by fully tested and operationally effective Me-262 that will not be shot down while landing because a flock of Me-109's will be guarding their runways.
America still has to cross the Atlantic. Production of the newest types of U-Boats would increase dramatically, this must be taken into account.
German tactical airpower will be moved to France and Italy, and Richthoffen will begin a limited counter-bombing campaign of British air fields and ports backed up by V-weapon launches.
Oh, and Japan. Under this scenario, Britain and the US will not be able to devote the level of resources to the Pacific as more and more assetts will be required to defend Britain. Japan might have time to finish her defensive lines and actually figure out how convoys work.
So, yes; if Russia fall, Germany wins. Unless Germany is overthrown from within.
If the Soviets fall- considering the Western Axis now occupy a larger area of GDP than Britain and America combined (of course, there were more in the allies than that- but let's face it, Canada, SA, and Australia are a drop in the bucket, and Latin American Nations had few troops on the front line, and were mostly coerced) the war is at best to result in- a cold war, and at worst, an Axis Victory, with the USA facing massive civil unrest, and Britain in full revolutionary Socialist Mode (Basically- this:
The only chance is a ruthless campaign to bomb Germany flat before it can unleash the economic power of Eastern Europe, then blitz though Western Europe- at a time when the USA itself had still not fully unleased its own military potential.
A tall order. Though, to be fair, not much less tall than defeating the Soviets.