IL, I think your argument assumes too much. First, that England would have surrendered. That seems very unlikely. After Hitler broke all of his previous treaties and promises by invading Poland, what assurance could Britain reasonably have that he would honor any armistice Britain could agree to? Absolutely none. Vichy France negotiated because, after all, what choice did they really have? With Britain, on the other hand, Hitler either needed to commit to a full-scale invasion and put the USSR on the back burner, or vice versa. He could not realistically do both. Absent an invasion of England, actual or realistically threatened, I don’t think England would have surrendered.
Your argument also assumes that England (and the US) would have stood idly by while Germany smashed the Soviet Union. Even as much as the USSR and Stalin were distrusted back before WWII, did they trust Hitler any more? Would having Hitler control all of Europe (save Britain) AND Russia have been acceptable to the US and Britain? I hardly think so. Britain would have found some pre-text to re-enter the war, even if she had signed an armistice.
UK would not have surrendered, but Germany would still have taken the alternative advocated by Admiral Raeder which was to go after British colonies and take Gibraltar and Malta effectively turning the Medd under total axis control.
WE CAN assume the Germans get 1 year to fool around and theirs little doubt that Turkey would be encircled by axis puppet states forcing them to sign on as allies.
England would have fought from Canada trying to get back England… rather than worry about France or any German success in Russia
German control of both Persia and England would have meant no aid going to the Soviets
Hitlers plan was to either defeat the Soviets forcing the British to come to terms and allow Germany a free hand in Europe… or a direct attack on England.
Remember Hitlers actual intention was to defeat the Soviets so England would come to her senses… USA only got in the action after Dec 7th… w/o that FDR could not convince the Americans to save Europa a second time even if England fell. Im sure that after about a year of more incidents American propaganda may have produced a limited war, but not before the Soviet would have fallen.