A double edged sword here, and a what if topic, but IF Hitler decided to invade, say the following year........ or so. Would there have been a difference as to forces, training and better arms?
I have always wondered if the Germans would have "caought on" to the T-34 somehow, then kick the Panther and Tiger up a bit more, or other designs, let alone other/ more (basic) men and equipment, maybe strike with a bit longer campaign in mind, and consider winter Russian fighting as well?
Russian would also have a year advantage to get their higher command in order from the purges, as well as train more and study the "German" way of war, I.E. Hitler and his generals. Maybe Britian was subdued or a treaty signed to that effect, then focus on Russia, I'm no expert here, but these are a couple of my thoughts on this for now at least.
Cheers
Tom