Great thought experiment. John Brown did conduct the real thought experiment and we know where that got him. Other uprising also happened of black in South Carolina, Mississippi, etc. Never turned out well for them.

Just as a footnote, as visitor to Dachau and minor student of Nazi Germany, we tend to forget that the vast majority of Jews were killed after early 1942 when the Final Solution at Wannsee was planned. In fact, the number was 5.7 million between 42 and 45.

But slave labor in Germany rose from the beginning and by 1944 slaves were 7.1 million. Slavery was actually one of the main reasons for ethnic dehumanization of Jews, serving a dual purpose: slave labor is free of course, and since Germany was economically devasted, Hitler could build the autobahn highways and the poor all the steel for war machines using free labor.