Imo, the initial question is not precise enough, it’s not about Germany winning the air war against UK, it’s about “eliminating”, or at least removing UK as an enemy, it doesn’t matter if sealion are executed or if some German assassins kills Churchill and the other prime minister will make a deal with Germany to be allied with the Germans, or to stay neutral.
But obviously, if there was any successful sealion operation, ……I would would probably be much better at typing in the German language then in English, even if you can see that English is not my first language…Norwegian or swede or any other nationalities, a German victory against UK would be devastating.
If Germany wont teh WAR against UK before any war against Russia, the odds of Germany winning is much higher.
Japan could not win anything from the US which is not giving away for free, but if Japan choose not to engage the US, but Russia instead, it could take 10-30 years to win a lot of square km2, but it could be (possibly) done.