Yes, we are unlikely to get to a point of an 1800s civil war, of course. But I mean, if things do get
that bad, we cannot rule out a divided military as well. How that would work in practice, I'm not sure, since, as you mentioned, armed forces work these days differently as well, and defection like that might not even be feasible, I guess.
Overall I would say civil war is more likely (even given how unlikely it is) than just a robotic uprising that will root out all humanity and make the world unfit for biological beings as the original comment implied.