Good summary by Mark Danner in the New York Review of Books:

Is Donald J. Trump really what the whole long age was gradually making for and meaning? That a reality television star and businessman con artist devoid of public office experience and proudly ignorant of public policy, of braggadocious and offensive and unstable character, given to the most bald-faced race-baiting and misogyny and demagoguery, could nonetheless be elected by our fellow citizens president of the United States?

It should be observed that this is not a question that will be answered by the election itself. If Donald J. Trump is not elected president of the United States on November 8, we will owe this not to some triumph of the superior American system or to the eloquent presentation of a progressive alternative but to the fact that this singularly offensive man offended too many voters, especially white, college-educated women. It will not be because he was rendered unelectable by virtue of his lies and race-baiting and immigrant-bashing and demagoguery.

On the contrary. Trump embodies grisly aspects of our politics that are not new but that, on him, are starkly illuminated. What are these? That much of our politics in this increasingly diverse country pivots on the hateful fulcrum of race, of racial fear and xenophobia and antagonism toward the Other, and that this has only grown in power and ugliness since the rise of Barack Obama and his coalition. That in vital matters of gender and sexuality and marriage much of the politics of the presiding culture is furiously rejected by a significant minority of the country as a “politically correct” and immoral imposition. That in the aftermath of a severe economic crisis—and after decades of economic stagnation for most Americans—tens of millions of voters feel so abandoned by the system that they offer their full-throated cheers to a candidate pledging to wholly dismantle it and put “in jail” his opponent. That the electoral system as it has evolved over that time and especially in the wake of such decisions as Citizens United has become starkly, shabbily, and spectacularly corrupt. And finally that entertainment and money in the grossest sense play a far more important part in our politics than any attention to public policy, and that the commercial press, particularly the broadcast press, battens on that reality to an increasingly shameless degree.