@Carl Schwamberger : I agree totally there were a non-trivial number of Nazi sympathizers in the USA, especially in some of the upper crust. However overall, they number of real sympathizers was not that large, and while some folks would be happy with Nazi actions towards Jews, Gypsies, and Slavs...
Quite true. I think its easy to see the diverse political views in the US would make a firm policy in any direction difficult. Ultimately it might depend on nazi economic success or failure. While some businessmen like Ford were still having success in Facist Germany & had profits there 1939-41 most US businessmen in the European trade had increasing difficulties and trade with German dominated Europe declined from German policy as well as the British blockade. If in a post war nazi Europe trade policy is not to mutual benefit and US trade with Europe does not recover to 1920s levels, or at least 1938 levels then tensions will be greater.
Theres also the political effects of a mass of Europeans fleeing to North and South America. While the US and others would take some restrictive measures a lot of smart and capable people will still enter and have a effect on US and latin American political direction. Even that they cannot vote their voice would tend to counter balance Facist or pro nazi proponents.
Wouldn't United States view Germany as a threat given its free of any need for a massive army and could theoretical build a navy to surpass the United States and Britain after a few decades.
There is this. If Germany is aggressively pursuing trade in Latin America and other regions the US is attempting to substitute for Europe then a larger and global capable navy may be pursued.
We also can't follow the thinking of Hitler to far in this. His health may fail, some Heydrich like individual may 'replace' Hitler. A more aggressive policy towards the US than Hitler rambled on about may be sought under different leadership.
If on the other hand the nazi leaders sit back to enjoy their spoils and build bigger palaces, squabbling with each other over their new empire. Then the US, Japan, the former British Dominions and the remaining European empires like Portugal would be building a new global economy, while Facist Europe stagnates and becomes less relevant in the larger world. So much of this seems to depend on how the nazi or European Facist leadership develops post war and what policies they develop.