The whole point of everything Hitler did, foreign policy-wise, centered around invading Eastern Europe and the Soviet Union and destroying communism. The only reason he entered into an alliance with Stalin in the first place was because Britain and France were going to go to war if he expanded any more – this being after Germany invaded Czechoslovakia and violated the Munich Agreement – and he wanted to avoid a two-front war after he invaded Poland. If Hitler doesn’t invade the USSR, then there’s no point to anything he did, because that was his end game in the first place.
I also doubt he’d be holding on to Western Europe for all that long, either. Churchill already committed the UK to the war, FDR was doing everything he could to drag the USA into it, and there was no way Stalin was going to stand there and allow a powerful, ideologically-hostile Nazi Germany to exist on the borders of the Soviet Union. If Hitler doesn’t invade Russia that year, it probably means a longer and bloodier WWII, but Nazi Germany was screwed regardless. It did not have the resources to beat the combined forces of America, Russia, and Britain all at once in a total war.
And Hitler was not taking London. Germany did not have a navy capable of supporting an amphibious invasion. The best he could hope to do was force a negotiated peace, and that already failed.