Removing Hitler from history might not have the effect your thinking of. Someone worse (yes, worse!) could take his place, and not be dumb enough to get into a land war in Asia.
I agree; suppose that someone Hitler-like but not as insane took his place. I'm reminded of a short story in which a time traveler goes back to ancient Greece to give them the beginnings of modern technology. He figures we'll have starships when he gets back to the 20th century. To make a short story shorter, he winds up scaring the pants (togas?) off of the philosophers of the day, and they won't touch science with a 10-foot pole. When he gets back to America in the 20th Century, science has been set back centuries, and the Indians are still in charge of most of North America. The story ends with him looking at a sign he's hung on the wall of his room, which says in English (a language that no longer exists) "Leave well enough alone!"
That’s what I’m thinking. The reason people are outrageously successful, even the evil ones, is because they tap into a strain of popular thought.
Like the free market, often someone else will come up with the same idea.