On May 10th 1940, on his way to the meeting with Chamberlain, Halifax, and Margesson, Winston Churchill dies in a car accident. How does this affect WWII and beyond?
That I think is a mighty big topic.

Halifax as the new PM is a topic I think we have cultivated for many years.

It is interesting if - in the situation at hand - Chamberlain is encouraged to struggle on until elections can be held.
Dunno' how possible that is, though.

At this time Chamberlain is fully behind any war effort as Hitler really stamped on his feelings after Munich.

That said, Chamberlain was not as inspiring as Churchill.

(Wonder how his … fight on the beaches... speech would be?

"Considering the hostile environment, it can be said that German aggression might extend to the very near locations of the empire, even up on the beaches. And that is where we must meet them …")

OK, that was funny.

Would any new PM send more RAF squadrons to France? RAF was not happy with bleeding the home defences).

Could Eden have ascended at this time?

Stalin meeting Chamberlain?
Stalin meeting Eden?