He attacked Russia because it was part of his grandiose and megalomaniacal plan for a greater Germany with libenstraum.
What difference does it make if the US declares war on Germany rather than the other way around?He will not declare war on the US, there is no need for that. The war was declared because Barbarossa failed and he desperately needed more time to defeat Russia.
The US will have to declare war itself, committing an act of aggression.
More like a B-36 first flying in late 1945 or early 46 because of wartime production rather than slower peacetime pacing. The US would also be going to jets and outpacing the Germans in that field except in high speed aeronautics where they'd still be catching up some. By mid 1945 the US had exceeded Germany in jet engine development and would have continued to outpace them.Here we have:
1940 - the fall of Britain,
1945 - first American atomic bombs,
1948 - the B-36 arrives (it wasn't called a billion-dollar blunder for nothing).
They'd be doing it under Allied attack. Just because Britain was gone as a base doesn't mean the Allies couldn't find alternative ways to attack Germany.So the Germans have at least five but more likely eight years to produce masses of fighters and bombers they need (as they actually intended).
The Germans were so far behind in this field it hurts. They weren't getting an atomic bomb anytime soon. They had next to zero enrichment program for uranium, didn't know about the alternative of plutonium, and didn't even have a working reactor to do research with. The design of the one they were working on was almost sure to be a failure.They have time to produce their own atomic bomb.
That's the one shown here.
At a reduced rate at best as most of Europe isn't going to be particularly willing to help them. They would have roughly the same base of manpower they had historically as well.They have the resources of entire Europe at their disposal, millions of determined and courageous soldiers.
That's fine. Let them live in the ruins then. Wiping out major portions of the economy would have an effect on fighting capacity. For all we know, the Allies in this situation might focus first on ending Germany's ability to fight any sort of war at sea. They turn the U-boat campaign into a slaughter. Once that menace is finished and over, they then use freedom of sea movement-- Germany having no navy to counter things with-- to launch nuclear strikes from ships at sea.The people who heroically fought even meters from the center of Berlin will not surrender because some of their cities are going to be destroyed.
Or, the Allies having intercontinental and long-range very heavy bombers use simple standoff missiles to deliver nukes.
The problem for Germany would remain that they are land power engaged in a war with several other land powers (USSR and US) as well as several sea powers (US and Britain). Even with more of the economy of Europe at their disposal that doesn't change. It means they are a one-dimensional strategic power facing a multi-dimensional enemy. Germany loses.