If things had been different and the Nazi Governement had reached a peace settlement with the Britsh government in 1940/41 what would the likely response of the U/S administration have been? What would have been the future of international relations in a world that would have had effectively three super powers? Namely Nazi Dominated europe, soviet Russia and the U/S.
There are a couple of flaws in that scenario: 1. The Soviet Union would never have ended up in a peace settlement with Germany, that was a fight to the death, you could have had one or the other end up a superpower but not both.
2. What happened to Japan? Remember they were allied with the Nazi's so that would have had a great impact on the US actions. Germany declared war on the US right after Dec 7 1941 but if they hadn't perhaps this would not have been an issue.