That being said, my number one concern is not the looting and rioting of the early collapse. My Lovely Wife and I are far enough from the center of the city, and likely areas of looting and rioting that I do not foresee prolonged contact with it as a security threat.
The number one threat to survival is from local law enforcement. I don't want this to be exceptionally paranoid, but I have grave concerns in this regard. When the established order breaks down, there will be a portion of the population that will engage in openly criminal acts, in large numbers. They will be violent, dangerous, and difficult to control. There will also be a portion of the population that will continue to rely on the local constabulatory force for protection. These people will be vocal and expect results.
Local Law Enforcement will be put in the unenviable position of needing positive action, but being unable to control the rioting crowds. This is where I read a threat from. I fully expect lesser violations to become very harshly punished, in the hope that it will be read as 'tough on crime.' It is very similar, in many respects, to the attitude of the NYPD towards firearm owners. In recent months, more than one person has been detained while carrying a firearm in New York. They have been dealt with quite harshly; moreso, perhaps, than the average gang member or drug dealer in the same city. People that are largely law-abiding citizens, who break a law accidentally or incidentally, do not have the ability to plea down a weapons charge. Career criminals, however, who break the law willfully and on a daily basis, have a range of options; bigger fish to sell out, in return for getting a lesser charge or at least a lesser sentence. Upon their release, they can return directly to their previous activities. For a law-abiding citizen, ANY felony conviction results in their loss of constitutional right. Being law-abiding, many of them will continue to abide by this ruling. Criminal actors, however, will continue to own weapons, even though they are disallowed by law.
In similar form, a basically law-abiding citizen, when confronted by police will conform and obey. This is much safer for LEOs, and will result in an increased arrest rate, conviction rate, and generally good press for the Department. Looters and rioters, on the other hand, will fight back, possibly resulting in injury to Police officers. Suspects injuring and escaping the police will not be good press, it WILL be dangerous to the officers, and will result in further pressure to show positive results. I can't explicitly blame the officers for these tactics, because it is also a matter of their safety and the continuity of our culture.
My example for this activity, even more than NYPD, is post-Katrina New Orleans. In a time of lawlessness, when the police force was faced with a total inability to deal with the very real threat of armed looters, they chose to disarm the orderly. SWAT teams kicking in doors and tackling old ladies, while a few miles away armed youths looted stores, was not the intended action (I hope) but it became a reality. I do not anticipate any other reaction in any major city.
End Result- watch yourself out there. While one would think that the cops have much better uses for their time in a pre-fall situation, in reality that will not be the case.