I think your fear is the largest one but I also think there’s a nonzero chance of a civil war resulting from the 2024 election.
As I’ve said let’s assume 2024 plays out identically to 2020. Are we sure republican legislatures in swing states won’t declare the Republican the winner in defiance of the popular vote? I’m not. In that case there would possibly be competing claims to the presidency, both with some merit. What happens then? I’m not sure but there seems to be an atmosphere for civil conflict there.
I can see terrorist incidents from whichever side ultimately loses the dispute over who will be POTUS, but I'm not really sure how anything like a civil war even starts here. Without secession this time. So what happens, a bunch of people on each side get together and form an army, then who do they attack and where? What role does the military and national guard play? How will each side even know who is the enemy? Will their be uniforms to tell us apart?
A "civil war" in the classic sense is just not something I see as a terribly likely outcome here.
Don't get me wrong. I think we're very likely facing political violence in the near future, just not that way. So, for example, if Trump goes to jail, I can see the far right plotting terrorist attacks which could result in mass casualty events. Like in Oklahoma City, or a political assassination like those guys in Michigan were planning, but where they succeed.
Such a thing would likely discredit the far right and result in shrinkage. After the bombing in OC, the militia movement reduced in size by two-thirds and did not start coming back until Obama was elected 10 years later. That is one theory of how we "win" this. First there has to be blood which is shed by them. Which is why I have been saying that it's nigh impossible for this not to get worse before it gets any better.