I'm not sure America would have used bombs on Germany. Dropping them on Japan was a totally different prospect. Japanese were asian and racism was far more widely accepted and even culturally ingrained. I think the decision to drop bombs on white Europeans would have been far more difficult. ESPECIALLY if bombs had been dropped on Japan already. In addition, the strategic impact of atom bombs at that point in the war against Germany would have been dubious. The German cities were already basically rubble, and as a tactical weapon, it is debatable how effective dropping nukes on dispersed German forces would have been. Not to mention dropping them anywhere near the front where friendly casualties would have been nearly equal.
To a large degree, the destruction caused by early nukes was comparable to the firebombing of some cities. The nukes were partly for shock value vs the Japanese and partly to demonstrate our capability to the Soviets before post-war lines were drawn on the map.