I find Hamilton to be a little dated as one would expect. The tradeoff between a militia and a standing army may be a red herring even for his time. The threats today that require a militia are the ones that can be reasonably deterred by the militia, That includes the government to a small extent but mostly criminals, would-be rioters, and mass murdering lunatics. It would also include foreign invaders with the modern caveat that foreign invaders can lob missiles that can't be countered by the militia.
I suppose Article IV Section 4 could give cover to states to use the militia as a local police:
The United States shall guarantee to every State in this Union a Republican Form of Government, and shall protect each of them against Invasion; and on Application of the Legislature, or of the Executive (when the Legislature cannot be convened) against domestic Violence.
-PJ
To continue the point, I don't think the term "militia" is meant to be singular. It is a regulated body of people. In other words, I don't think that George Zimmerman protecting his neighborhood against Trayvon Martin would be considered a militia action.
A militia cannot be seen as a vigilante group. Multiple independent armed people are not a militia because they are not "well-regulated." As Madison states, they must gather periodically and practice. Practice means three things: 1) demonstrating that the arms are in proper working order, 2) demonstrating that the people are skilled in the proper operations of the arms, and 3) demonstrating that the people can act as an organized body during a call to action.
Individual policing would be hard to bring under the umbrella of a militia unless those people also participate in a regular militia order from time to time.
-PJ