I think things will need to be dire indeed before we see anything though. Carry on the balkanization a couple more decades and then throw in a real economic catastrophe like the Great Depression, i.e. >25% unemployment, starving people overwhelming what social services are left. Then there might be fertile grounds for a bloodbath.
Assuming I remember correctly, the year or two leading up to the American Civil War averaged something like 40 politically motivated killings per week. We’re certainly polarized and moreso everyday but fortunately we’re not yet experiencing an equivalent bodycount.
