If the "great beast" and "great battle" appear only in a second+ draft written during the war (and never even published) maybe that show that he had no plans to go to war with the US in his original vision (from before the war). I still believe before the war Hitler only wanted Europe and he thought Brittain could have the rest of the world. During the war that might have changed ofcourse and it is likely he would be preparing for a final battle with the US.
Edit: A funny video that fits well in this thread.