When Guderian presented accurate numbers for Soviet tank production, Hitler got miffed. Even claiming that if those numbers were correct, they had already lost the war.
A lot of it came from the disasters in the Finnish war. Even Beck from Poland, right up until August 1939 totally disregarded any Soviet ability to help out.
It might have been true in 1939 and 1940, but it did indeed start to turn, and turn fast.
So, paper bear, well, yes, depends on the timing.
Another side remark: Whemn Hitler saw the Czech defences, he exclaimed that if he had known how strong those were, he would never have played hard ball as he did.
We have had a thread on WI the Czech had stood their ground and got into the fight instead of giving up in Munich. Some 28+ divisions behind the "Eastern Maginot line" as it was called, would have been a match for Germany in 1938.
Anyway, I can see that a German invasion might fail after Dunkirk. Tanks starting to be worn out, lack of transport, and then facing fresh French troops from the South.
If the re-insertion of BEF then is reasonable successful (Brooke's second trip to France), it could perhaps become reality.
That said, we have also had a thread on WI France never capitulates but the Gamelin plan actually is implemented, trying to hold out until spring, etc. The stuff that Brooke said was not feasible.
Ivan