So what does "marginalization" look like? How does one go about marginalizing? (This is a sincere question, I hear the word used a lot, and I'm not sure what examples are.)
One thing to keep in mind is that the ideas generally associated with Nazism (nationalism, racism, expansionism, aggressive invasion, etc.) have already been marginalized in the eyes of the general public. A lot of the old ideals of "Americana" have also become marginalized, such as the romanticization of the Old West, the Antebellum period, the Lost Cause, Manifest Destiny, US expansionism. These ideals have all fallen by the wayside and are generally looked down upon by most Americans these days. They are seen now as ideals largely fostered by ignorance - and now that most people know this and recognize it as such, it would be extremely difficult to get the general public to turn back the clock. It's only when people don't know any better that such ideals can flourish and come to power.
The other side of this is that the economy has to continue to remain viable. Nazism probably never would have come to power in Germany if their economy had not been in such a shambles. People can be talked into accepting the unacceptable if they're desperate enough and hungry enough. Logic, reason, compassion, conscience, and morality will all go out the window under the duress of economic instability and deprivation.