At that point, with Soviet forces pounding through the outskirts of Berlin, there is nothing that could have changed the direction of the war. The Germans had no air force left, no functioning economy, no well of available (let alone trained) manpower, nothing but the scraps left in the field. Even if some unimaginable force had removed the United States and the USSR from the map, the Allied and Soviet forces in theater had the resources to continue fighting until the unconditional surrender of Germany was forced.

This might be better asked in /r/HistoricalWhatIf.