The biggest evidence of Germany winning a future war is that in the 21st Century the Hohenzollerns are still ruling Germany. Considering how vengeful the French are, there's just no way the Hohenzollerns would be allowed to keep their crowns in the event of an Allied victory. And before you say 'Japan kept their Emperor even with how vengeful America was after WWII', that's apples and oranges. The Emperor of Japan has a unique stabilizing factor over his country that the German Emperor does not have, thus none of the Allies would have any reason to preserve the German monarchy in the event of their victory.
Also, note that in late-20th Century, Germans are explicitly still mentioned as celebrating their victory in WWI. There's no way they would do so if they lost the next war, as a postwar Germany would be indoctrinated ala OTL into seeing their past as pure evil until they were hammered flat and then remade in the Wallies' image.
Ditto for the Ottoman Empire. The Ottoman Empire is shown alive and well in the 21st Century, and most terrifying of all, is able to openly deny the Armenian Genocide in a way even modern Turkey cannot. And there is absolutely no way the Ottomans would be around and able to do that if they and the other CP lost the next war.
Also, note that in late-20th Century, Germans are explicitly still mentioned as celebrating their victory in WWI. There's no way they would do so if they lost the next war, as a postwar Germany would be indoctrinated ala OTL into seeing their past as pure evil until they were hammered flat and then remade in the Wallies' image.
Ditto for the Ottoman Empire. The Ottoman Empire is shown alive and well in the 21st Century, and most terrifying of all, is able to openly deny the Armenian Genocide in a way even modern Turkey cannot. And there is absolutely no way the Ottomans would be around and able to do that if they and the other CP lost the next war.