America! What a prize to gain for the Germanic race!
Hitler gets a realistic lasting impression of American power from the visit, so he vows to himself never to get the Third Reich embroiled in a fight with the USA if he can avoid it.
It could also work the other way 'round. Hitler is impressed by the American potential and the wide open spaces, much friendlier than the Eurasian Steppe. He is also intruiged by the legacy of slavery in the South and the high percentage of Americans of German descent.
He revises his Lebensraum-policies and German strategy turns Oceanic. The Hitler-Stalin-Pact gets widened to incorporate Japan.
On June 22nd, 1941, Soviet armies cross the borders into Afghanistan and Persia while German and Italian forces assault Malta. Shortly afterwards, Turkey joins the Axis.
Hitler receives news of the Japanese attack on Pearl Harbor while on the way to Madrid where he is to meet Franco again.
At that time, the Russians have pushed far into British-India already while German and Italian forces safely control the Mediterranean Sea and most of the Middle East, although there is still fighting in Southern Iraq and Saudi-Arabia.
The Luftwaffe enjoys air superiority over the skies over Europe, with the exception of the British Isles. Still it regularly raids Portsmouth and Scapa Flow and the East of London.
British air attacks on Europe are rare and costly. They cannot hinder the massive German naval buildup...
Franklin D. Roosevelt has done what he could to arm the USA despite isolationsim. But now he is faced with a world where war is forced upon the United States and the only major powers which might be allies are on the verge of collapse. The Chinese are fighting on two fronts after the Sovjet Union has started to secure the Western half of China.
And his intelligence reports warn that Operation Sealion is probably slated for May 1942 - Northern France, Belgium and the Netherlands are full of airfields to host thousands of Sovjet and Italian, maybe also Spanish and French planes. They will be there to assist their navies on Tag T.