Point 0: WWII was the battle between evil and even more evil. The question is which side was which.
Progressivism has decayed using the 'minority rights to prevent mob rule' thing. They're employing more and more violence against the majority on behalf of smaller and smaller minorities.
How would Nazism have decayed? Perhaps they would have used less and less violence on larger and larger minorities? That would have been better than what we got, but it's hardly guaranteed. After they got rid of the Jews, they wouldn't have gotten rid of socialism. The problems would have remained, just like bagging the kulaks didn't made communism suddenly a good idea. They would need a new scapegoat, but the smallest minority was already defeated. It's just too embarrassing to dig up that corpse for beating. They could also have used escalating violence, just like progressives do, in which case it would have destroyed itself just like the USSR did. Lots of ways it might have destroyed itself, really.
At least the post-war infernal hell would have had good taste, instead of literal state-sponsored vandalism.