What if the 20th of July 1944 Hitler has been "terminated"

[PanzerJaeger]

The UK ceded Poland to the Russians because they had no choice. The same applied to the US. Neither was willing to risk a war with the Soviets over Poland, or for that matter any other Eastern bloc country. That's irrelevant to the discussion though because the UK, US, and France WERE willing to fight Germany over Poland. That's the entire point.

Well, the UK and France were willing to fight Germany for Poland in 1939. The US was only willing to fight Germany after Hitler declared war. Anyway, after 5 years, France was beaten and the UK had suffered severely. As you stated, the British did not really care about the Poles, they only wanted to contain German expansion. I think that with the Nazis out of power, Britain would have been more than willing to cede Poland for a "victorious" exit from the war, especially if it helped contain the second, now first, most dangerous threat to Western security - communism.

Caen had already fallen by July 20th. There was no longer any way for Germany to eject the Allies from France at that point. The US breakout along the coast started less than a week later. No change in leadership was going to prevent that from happening.

It wouldn't? The Normandy campaign was decisively won a month later in late August with the Falaise disaster, which was directly attributable to Hitler.