On the German Question...

We can discuss strategic mistakes and missed opportunities by the Nazis all day long, but we can't do that without pointing out Allied mistakes, too. I'm game for either continuing the discussion of exactly when, in a purely historical context, Hitler and the Nazis crossed the line between fighting a fight they could win, and expanding to a war they could never win (and I still contend that it was the actual manner in which Barbarossa was planned and executed that put the final nail in the coffin, and not the invasion itself)...

OR...

We can discuss strategic possibilities for potential German success, given certain understood constants and parameters that we know from history. This takes us into the "What If" game again, and past experience has shown we don't tend to agree in this realm on what is or isn't "fact".

For example, as Jambo pointed out, had Hitler come to the same conclusion that Stalin did and removed himself from the strategic planning and operations aspect of the war effort, I have a sneaking suspicion that much of what we take for granted now would NOT be the case. Imagine what the defenses along the Normandy and Brittany coasts might have been like on the morning of June 6th, 1944, had Rommel had his way rather than be forced to do what Hitler insisted and separate commands between all forces on the beaches and the reserve armored units inland. What if command authority had remained with the officers on the coast, where the decisions needed to be made immediately, rather than deferring them all back to Berlin and the OKW?

One final point...

Ryan makes the case that the end of the war for Hitler was Pearl Harbor, and it is a good point... but to be absolutely accurate, you'd have to say that the turning point in this scenario was Germany's declaration of war after the US declared on Japan... and I'm not sure that wasn't the right thing to do.

Keep in mind that Hitler didn't want the U-boats sinking American vessels (even though they did, on occasion) because he didn't want to provoke American intervention in Europe, but once America was at war in the Pacific, and knowing we'd fight right alongside both the English and the French to defend their colonial and commonwealth territories, American involvement in Europe was unavoidable, so the shooting of convoys and American "Lend-Lease" targets after Dec 10th, 1941, just makes good sense, right? Why not force America into a two-front fight that could only detract from America's ability to assist and support England and the Allies?

Had Germany done a "secret attack" on the US by bombing New York harbor or Hampton Roads or Boston... then I'd agree. But in reacting to a Japanese act (that I have never been fully convinced was known ahead of time by the Germans), I think it was (objectively speaking, of course) the only strategically sound course Germany could take.