Despite the political turmoil, I'd say the likelihood is still low.

Highly unlikely, the closest I can see it getting is Troubles style car bombs, truck bombs, and maybe some homemade fpv drone strikes, plus a bunch of cops and feds beating and shooting people in retaliation.

I'd say close to 0. If it were the right, I'd say they'd be more willing to get violent. I don't think "the left" has the same kind of bloodlust or war romanticization as the right does. "We'll" just take it until it goes too far, then there will be riots in protest, but no actual "civil war."

*third civil war

Everyone forgets about the coal wars, and the scenario you are talking about will likely look very similar to that one.