The part about the war being turned around by the time we got involved. Had the US not gotten involved, there's no way Germany would've lost. Even with the 8th Air Force the bombing campaign came close to being called off due to loss of aircraft and men. There is no way in Hades that Britain could've mounted a credible air campaign of any significance on its own. They were reduced to a second hand role bombing at night due to the vulnerability of their bomber aircraft. A landing in Europe would’ve been completely out of the question for the British.

As for the Soviets, had the vast bulk of the Luftwaffe been freed from air defense over the Fatherland, Germany would’ve held complete air dominance over the plains of Western Russia. We know firsthand how badly German forces were mauled by US airpower in the western theater, now imagine if Germany had been in a similar position in the East. Add to that the lack of damage done to German industrial centers, population centers, and oil production in Eastern Europe from US bombers, and the situation swings heavily in Germany’s favor.