They are shutting down the subways so I doubt inner city hoodlums are waiting to invade. (Oddly enough, I've never heard of an inner-city hoodlum robbing Harry Winston's!) Now if the apocalypse DOES happen, looters will probably rob their own neighborhoods. That, sadly, now happens in every American city.
When Hurricane Katrine hit, there was looting in upper class stores and stories of severe vandalism.