How much steel will go from building Panzers to building landing craft? Also, have fun getting all your multi-engine pilot instructors killed when their JU52s are bounced by the RAF
See Tooze, Chapter 13, "Preparing for Two Wars at Once". The industrial requirements for Barbarossa, to be completed by May 1941, were set in something called Ruestungsprogramm B in which exports were increased but the number of army divisions also increased from 143 to 180. Between the fall of France and the invasion of the USSR, the German army steel ration fell by 1/3rd, to cover the boost in export production, even as its striking power increased. German army manpower at the end of the French campaign was 5.7 million, which increased to 7.3 million by summer of 1941. Ammunition production was 36% of the German army's steel budget, falling to 20% by summer 1941 due to the overstock caused by the unexpected suddenness of the French campaign. The German army steel ration for the 3rd quarter of 1940 was 305,000 tons of a total production of 1,885,000 tons of steel. Ammunition production was roughly 90,000 tons of the 305,000 tons, falling to roughly 70,000 tons in the second quarter of 1941 (20% of army steel allocation).
Total requirement for a landing craft program for summer 1941 might be something like 100,000 tons of steel, with at least another 100,000 tons for the second half of the year. Ammunition production between July 1940 and June 1941 was roughly 318,000 tons of steel. So the answer to your question generally is that ammunition production would have to fall, the armaments to expand to 180 divisions would need to scale back, while labour inputs would need to increase steel production. Without Barbarossa then army manpower, instead of rising to 7.3 million for Russia, might fall to something around 4.5 million. That's a net swing of 2.8 million workers demobilized and entering the work force, which should allow steel production - and industrial production in general - to increase.
None of this mattered for 1940, of course - industry could not deliver anything but an ad hoc solution that year.