I'm with you on the parallels @Smokin Joe , and I think it *could* happen here; we aren't genetically distinct from the Germans of the inter-war period. Like you, I used to wonder *how* that could have happened, but then I saw the Democrat party fall into lock-step behind Clinton regardless of what he had done, and I saw the hero-worship afforded to Obama regardless of his clear lack of qualification, and I see the same now offered to Trump in spite of the many qualities, statements, and actions which should disqualify him. And all three instances are characterized by appeal to fear and envy, and by scapegoating others and creating enemies. American politics are clearly breaking down, or perhaps *have broken down*, into recrimination rather than competing ideas about governance, and I think it does sow the seeds for the kind of future you are describing.
But I think the major sees those same things also, he just sees that they are far more developed on the left, and that not all of the necessary parallels are in place for an American repeat of that history. Now if, as the major points out, it has happened on the American left it can surely happen on the American right (or whichever direction we ascribe to Trump's supporters) as well, and I agree with you that we can at least see the leading edge of that tendency in some aspects of Trump's campaign. You're also right that it's the kind of thing we should resist and defeat before it takes root, not after. But if it hasn't yet taken root, then clearly it's not yet the full grown plant, and I think that is the major's key point.
I just hope that thinkers here on this site who have displayed a lot of insight and critical thought, and I put you and the major in that category, won't fall out with each other when it doesn't seem necessary. However this election turns out we'll need fellows like both of you helping us find a way forward.
On the right, I see that the anger has been there. No one wants to be a victim on the right, no one wants to blame others, but that is a seductive stance.
Circumstances have mounted to the point the folks on the more Conservative end of the political spectrum are sick and tired of being used as a scapegoat (anger).
Tired of being blamed by those they support with their tax dollars and increasing national debt, often in relative luxury to what they themselves can afford. (anger/resentment)
Despite all those forcefully extracted benefits, those who decry the selfsame people who have by and large crafted this nation want yet more. (anger/resentment)
Our very communications are garbled and delayed by entreaties to have them in an alien language, foisted upon us by those who are here illegally or who refuse to assimilate within out borders (anger).
Our economy stinks, especially for the formerly middle class, often stripped of employment opportunity by a combination of overweening government policy, but blamed on the invaders. (anger)
Our culture is under attack by 'refugees' who carry the same seeds of belief as our enemies. (anger/fear)
At every turn, the actions of those who hold the same beliefs as those we fight elsewhere, perpetrated here are waved as an excuse to yet again attempt to disarm US. (anger/fear).
Our country is fighting a long war, often hampered by our own government, at the cost of our sons and daughters lives and well being, against the very peoples who are being imported (through our tax dollars) (more anger).
Our military is being used for social experimentation, seriously hampered by rules of engagement, and despite being the most effective such force on the planet, suffering in prestige due to the treatment of our warriors by their own command structure and the demands placed on our troops in other countries and upheld as US policy. (more anger)
At home, rioters and looters, operating with impunity under false pretenses and with apparent official sanction based on race, destroy whole neighborhoods while blaming those who attempt to maintain order, who are even targeted by the rioters or those sympathetic to their cause. Laws are selectively enforced, by the command of politicians. (more anger)
Just because the veneer of civility hasn't worn through to the point where there is mayhem in the streets, doesn't mean there isn't pressure building in the cooker. Let some Fergusson style riot get out of bounds, into the wrong neighborhood, and the shooting will start. That would be the excuse which will justify anything from calling out the National Guard to blanket Marital law and the enactment of weapons bans.
The dominant culture has resisted retaliation, but that doesn't mean the stage isn't set for one pivotal event to change the landscape.
The American Left is like a fault line which has its regular, small scale seismic events, bleeding off pressure, but not achieving a fugue state. The other side of the political spectrum, however, as evidenced by growing genuine racist tendencies in posts on other boards, is harboring a smoldering resentment against those perpetrators, one which is building stress along the fault lines so thoroughly established by the Left, itself. That has not been relieved by incidents like the stresses on the Left, much of which was blatant theater for looters and race pimps.
When/if the stress on the Right lets go, it will be a major seismic event. Until then, a bulge here, a crack there, but no earthquake. Little shocks might rattle the dishes, but the big ones bring down the house. Chaos is the environment in which profound change commonly takes place, often not for the better.