I think that generally speaking there are too many moving parts in this for anyone to give an easy, simple prediction, without knowing how and why the Nazis won, etc, etc. What ever the Nazi leaders planned to do does give us some inkling of what they would have wanted to happen, in a dark, twisted ideal scenario, but then the objective reality would have intervened in a plethora of ways to influence what the real outcome of their plans would have been. Like it did IOTL.
On the other hand, I think that if one asks such a question, with the qualifiers "Nazis won the war and ruled Europe up to the Urals", "Germanization", "exterminated" and "Generalplan Ost", one has already decided the range of damage, though, which would be somewhere from between horrible and hellish. In that case, one could just make up numbers for an inventive worst case scenario ("70% exterminated, 20% neutered and lobotomized for a disposable slave underclass, 10% Germanized").
The realism of the whole scenario is another matter entirely - what you are in essence asking is "in this hugely unrealistic scenario, how would this particular theoretical process realistically pan out?". In other words, it is a scenario and a question that is already seriously undermined by its premise.