It's the start of World War II. What would've been impossible for 'experts' to predict?

Let's set the scene. It's the 3rrd of September 1939. Great Britain has just declared war on Germany. Much like how today's media employs 'experts' to predict how political events will end, you are an expert on world affairs and you are asked to predict the course of the war, based on the information at the time. You are unaware of what's going to happen.

What would you have predicted to happen over the course of the war and what would've almost been considered impossible? Would the events of World War II as we know it be considered impossible?
 
The experts would probably predict a rerun of WWI, especially as concerns a Western Front. Though Germany would probably do better due to not having to fight in the east, the combined Anglo-French forces, along with a blockade, will eventually wear Germany down. Everyone (including the German High Command) was stunned when Germany conquered Western Europe in six weeks.
 
Radar, sonar, jet planes, controlled nuclear fission, nuclear weapons, cruise missiles, ballistic missiles, speed effectiveness killing power (range) of tanks, proximity fused shells, etc, basically the scope of technological advancement from 1939 to 1945.
 
That Japan could run amok so completely and effectively against so called major powers with such a shoestring operational margin and even more parlous logistics.
 
The bloody mess that was the Eastern Front, all those people slaughtered. The idea that hell on earth was about to be unleashed may not have crossed their minds in 1939.
 
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