There are a lot of big IFs in your piece. The biggest one is if Trump runs and wins (even with all the cheating going on. There might be a third party spoiler that ruins all the GOP plans for a complete takeover). If people decide to fight in the streets. If the National Guard can't quell the problems. If the Democrats lose the Senate. If Biden and Democrats don't throw away the filibuster. I suspect that Biden will not play nice in 2022 as things lead up to a takeover by Republicans. Maybe things get better enough economically that people won't throw it all away on a stupid civil war. Democrats know it just as well as us. Trump proved that our democracy is very fragile. IF corporate overlord don't cut off funds to GOP and they can't be so greedy that they can't see this coming and cut off the lifeblood of Republican campaigns. So many things have to align for things to descend into chaos. I think the two biggest things are Trump actually completing a run for president (hamburgers and fried chicken aren't great for the heart) and the will of the people to take up arms against each other in a true civil war. When the dead bodies start to pile up on TV, will that change people's minds?
But, I can see it happening. It was a weird dystopian science fiction story years ago, but now is coming into sharper focus of a reality that isn't too hard to imagine. You didn't touch on the economic problems of a civil war. Massive collapse of our economic system and most likely the world. That's when the chaos and death will occur. I can see Russia annexing Alaska. China invading Taiwan, Korea and Japan. Civil wars breaking out all over the world. Maybe nuclear wars. All bets are off.