I agree that this system is more fragile than most people think; somehow almost preferring automatic government than the tediousness that functioning democracy requires. And sometimes people get a rude reminder of this.
I do not agree that the scenario you're talking about is probable (which is indicated by plausible). Perhaps you mean possible? Sure, but in that case it's also possible money instantly has no meaning, there is no Congress, there are no states, there are no judges or generals, there are no prison sentences, there are no laws at all whatsoever. Nothing matters, everything is possible.
That is a sense of unpredictability a society does not trend toward no matter how ill it is.
But try to understand that completely ending all constitutional order is not how revolutions tend to progress. Even in the U.S. civil war, there were two (federal) constitutions in place for two sets of states. There was order, even in that chaos.
I agree Trump has autocratic tendencies. But he is a weak minded fool. He will not make for a strong autocrat, he even contradicts himself and dithers too much for this. He is Side Show Bob. He's a distraction. To succeed he would need a very high percentage of authority, trust, and compliance - and there's just no way he's going to get that.
I question whether he even does something to sabotage the election. On January 20th his term of office expires. At noon he is not the POTUS if there's been no election. Further, there's no House of Representatives, because their term expires on January 3rd. And 1/3 of Senators are not Senators. But at 12:01pm on January 20th, there is a person who will become POTUS without an election. And that's the President pro tempore of the Senate. Following that, the states will surely already be figuring out how to reinstitute the House through either appointments or new elections. It's not up to the federal government. But to pass new laws, including a new election to make up for the delayed one, we'll need a Congress.
That has never happened. I can tell you many examples from history, things that are way more likely than any of this. Including from American history. Some of those things are violent, even in fact violent for just one person, that are way more likely than autocracy.
Trump's best chance is for the election to proceed.
So, while you can't for sure predict what's going to happen next, just try to have some imagination for rare events that have happened rather than events that have never happened. Trump is a chickenshit asshole but that's like, the least remarkable or interesting thing going on here, because he's been a chickenshit asshole his whole life - not news! And that doesn't really highly qualify (or disqualify) him as an autocrat. He's not going to be one because he's just too incompetent and steps on his own dick every chance he gets. Just try to calm down, let him have enough rope to hang himself, and he will.