Lots of interesting comments here.... I'll just say I think we ask the police to do too much. Deal with homelessness, mental illness, drug rehabilitation, all kinds of shit that they should be asked to deal with (in my mind) on an emergency basis. As it is, because of chronic underfunding or defunding they're basiclly being asked to remedy situations over which they have no control, no workable authority, an no funding. Societies with large disparities amongst have and have not, regardless of the cause, have large civil strife unless, and here's the unless, there is a vast and powerful mechanism for control that includes, at the base of the structure the willingness to use deadly force not against theives (who always take advantage of wide spread civil unrest) but against those who are demonstrating for change. (We can discuss Mexico here, as they're a good example).
Anyway, besides the posse commitatus act and other prohibitions of use of the US military on US soil, I have difficulty with doing that for the same reasons the founders and drafters did - the army has one purpose: to defeat the enemies of the nation as quickly as possible, normally by means involving near fatal injury and death. Because that is their purpose and focus, when confronted with any problem, including other citizens, the military response will generally involve death. It's not fair to our people, or our military to ask this of them. This is different than armed rebellion.