Realistically? It'll play out differently in different parts of the country. I suspect he'll leave MA alone, for example; he never had much of a foothold here, and he still doesn't (despite the mask-free woman I encountered at the supermarket).
But I am more and more concerned about a genuine civil war, and a shattering of the country. It's probably always been inevitable, but now it seems imminent.
I worry about this too, but ultimately the side that wins is the side that gets the military. We know the police will side with the conservative mobs in the streets but not liberal ones, and they certainly won't really be about keeping order or saving lives impartially.
But it will really depend on the military. I get the impression many military commanders aren't fond of Trump's approach to things, but rank-and-file military types tend to be very conservative. They have all been sworn to uphold the Constitution, however, regardless of political views. If Trump's power grab is blatantly unconstitutional and isn't backed by the courts, then the military would almost certainly side with the courts. I'm guessing the top brass wouldn't support him against a SCOTUS ruling, even if many enlisted are unhappy about that. It'll come down to how well disciplined they actually are.
White nationalists have allegedly been infiltrating
the military for years, so there could be infighting.
But if the courts uphold Trump? Then the military will likely side with them. The Constitution demands that, even if the courts have become so corrupt and partisan they'd side with someone who is clearly anti-constitutional. Our system has no mechanism I am aware of for dealing with corruption of all three branches of government. They were set up to be checks on one another.
Whichever side gets the military would win. Possibly the military could split regionally, with military bases going with their own states, but I don't see that as likely. The top brass will likely want to follow the Constitution, even if it actually leads them off a cliff. I doubt ordinary citizens could stand against the military for long, even conservatives who stockpile weapons in our garage. Even if the courts oppose Trump, though, and the military backs that up, it could be ugly for a long time. I'm afraid the military could put a liberal rebellion down faster, because we don't tend to stockpile weapons in our garage. Young people throwing rocks don't tend to do well against armed troops who feel no restraint at all. The older suburbanites who have a lot to lose are more likely to "tsk tsk" from the sidelines but ultimately hunker down and hope things get better on their own.
This is just a guess on my part of how things could go if Trump steals the election, or if he attempts to. I'm no expert in the military or politics, or even on human nature, so I could be spectacularly wrong. I hope I am. I am hoping Trump is handed such a resounding defeat in November that even he realizes the best option is to save face by slinking off and claiming he planned it this way all along. I hope that if he challenges the results the courts put it down quickly and most of his followers go back to 8 chan (or whatever it's called nowadays). I doubt they'll quietly retreat to the fringes of US politics again, however, no matter what happens.