Trump’s racism is not of the genocidal variety, and he is committed neither to a program of Darwinian racial conquest nor the principled imposition of one-party rule. If President Trump does start a world war, it would probably be as a result of blundering rather than a long-term master plan.
So Trump's possible imposition of one party rule would be unprincipled and he probably doesn't have a long-term master plan involving world war (Chait did not add that he makes this last bolded bold claim because he doesn't think that Trump is capable of long-term planning -- that would be a full gigaChait of shrill and I know I am going to have to brush up on my prefixes before this campaign is over).
Chait is 100% serious and makes a fairly convincing case for his (qualified) analogy. He isn't claiming that Trump is Hitler, but he is claiming that the Republicans who endorse Trump are fools or knaves, Hindenbergs or Von Pappens.
Trump’s admiration for ironfisted dictators, not only in Ba'athist Iraq but Russia, China, and North Korea, is the ideological lodestar of his long history of political musings. Over the years, Trump has weaved left and right on health care, abortion, taxes, and even the issues currently central to his campaign, like immigration and trade, but has never wavered from his foundational belief that strong leaders are those who crush their enemies without restraint. Whatever norms or bounds that we think limit the damage a president could inflict are likely to be exceeded if that president is Trump. Those Republicans who publicly endorse Trump because he probably won’t win may be making an error on a historic scale.