The "united states" of America won't exist. States will secede and declare themselves as independent nations. The international community will have to draw up new trade deals. A fascist USA is unlikely because there isn't a culture of authoritarianism that would tolerate a totalitarian state.
I'll use the example of Germany and France to explain what I mean.
Germany and France in the early 20th century were both extremely anti Semitic and hated immigrants. Germany submitted to fascism after the depression while France resisted it. Vichy France was constantly in turmoil because French people did not want to live under a dictator. They had a proud tradition of fighting back against kings, emperors, and other people who sought to centralize power. Germany on the other hand glamorized the holy Roman empire and Otto von Bismarck was seen as a great unifier of German speaking peoples(Bavarian, Austrian, Prussian). With how they structured their families, the German father had to be submitted to. It's very similar to a lot of Arab cultures where children and women were basically a man's property to do with as he wished. This fostered a culture of dominance and submission which primed the population to accept authoritarianism.
America is not like this. Conservatives are like this, but most Americans aren't. Most Americans actually don't give a shyt about the things these conservatives obsess about. I think you're more likely to see just unrestrained violence when people realize what's happening. Americans aren't docile enough to accept the kind of country these people want to create. There's a tradition in this country of fighting back instead of submitting to authority. We don't valorize the spineless, we don't praise supplication. We treat it with disgust. People want to believe whatever religion they want to believe, they want to move around freely, they want to say what they want, and they do not want to be beholden to people who want to tell them what to do with their bodies or who they can and can't associate with.