I watching Demolition Man, so the prospect of LA becoming a warzone with in the future year of 1996 (according to the distant past of the early 90s) has intrigued me, hence my bump.
I should comment of the views of skyrocketing crime rates. I think such a view in the 90s, and 80s, suffered from an oversimplification of humans and human nature, because it seems pure sociopathic behavior and psychopathy were often apart of these feared worlds. The problem with that is, most people aren't sociopaths or psychopaths, and most have motivations (whatever those motivations may be) rather than just being bad for evil's sake. I think that's a problem to work around to achieve dystopia as the 80's and early 90's viewed it. Perhaps behaviors we call evil and wrong (and sociopathic and psychopathic) could come into vogue as being supported by society and being what is taught by society to be ok and accepted, and that's be a way to work around it.
EDIT: Oh, and atop the "Escape from New York" megacity-as-prison, we could add "Cryo-Prisons" where prisoners are frozen. Although I don't understand the thinking behind that. I mean, how do you reform someone if you just freeze them in place?
EDIT EDIT to the former EDIT: Oh, and there's the issue of the Utopia that's Dystopic, where Utopia is achieved by means of suppression of some other element, often after the aforementioned regular Dystopian events occur. In "Demolition Man", it is through a hyper-Politically correct society where swearing, red meat, dirty jokes, staying out after curfew, and other things are banned (20th century things are considered contraband I believe), weapons are banned and only found in museums, physically touching someone else is considered odd and not done, and society is rendered neutered (and like "Leave it to Beaver" if the law forced you to act like that; graffiti to considered on par with how we view a murder in the present, and murder is like someone raped God and never happens), and those who don't wanna follow this way of life are pushed out, and forced to live in exile (Taco Bell is also the only restaurant in existence). In "Starship Troopers", its a borderline fascist society where citizenship is based on military service, and there's a possibly totally rigged war against an enemy that seems not really the instigator of the war.