Why? Do the police go away? Do people become murderous idiots because DC is burning? No.
The police will be faced with a dilemma. Given their decades long mentality of "Us against Them", they will have to chose whether to protect their paychecks and pensions by doing what their masters order, or do they join the citizenry.
You use the term "murderous idiots" and that may well be what you think of those of us who decide to stand and fight, but it shows me that this is little more than an academic excersize to you. This ain't tiddly winks FRiend, and any thoughts you have of a nice, tidy recreation of 1861, which is where our conversation started, are just dust in the wind.