Oh, the US is heading towards oligarchy. It's clear as day.
What I think we're seeing is a resurgence of fascism. Not the nazi variant, though, but the original, Mussolini-style form of autocracy that is essentially a non-ideologic blend of chaos, cruelty and pomp, topped off with cynical disregard for common decency and societal norms.
In short: institutional hooliganism.
America, most likely, will not be made 'great again'. It'll be sullied by people who simply aren't interested in such niceties as the common good.
The best we can hope for, I think, is that the US's institutions, its democracy, will prove to be sturdy enough to survive four years of this corrosive darkness, and that, in the meantime, there will be no violence in the streets.