Without American support—UK would have lost—Mosbey and his fascists would have been set up in the UK and a new—pro-German King set -up. US would have signed a treaty with Hitler and seized Canada. The world would be a very different place.
Hitler launched Barbarossa, on the theory that Britain had been effectively neutralized, and no longer a threat.
What he forgot was that after Pearl Harbor, Britain became the world’s largest Aircraft Carrier for the American forces.
As Bull would say: “Oooooookay.”