Calling "Organized Crime" for "Organized Crime" in post-acolpalyptic scenario would be wrong in my mopinion. They are basically just another faction of survivors. But as a GM I'd have any faction I could come up with controlling a small village,town,area,valley,hill etc, while other places would be in anarchy.
The power of said groups is probably determined on how long time they had in planing a proper fallout shelter(s) storage,fuel,ammo,food etc (spareparts)
If on the other hand the apocalypse (ww3) happened very quickly said groups would mostly be wiped out or find themselves as refugees....
I'd guess a mixup would be a good way to go. Like the Italians (Cosa Nostra) some of the families have been obliterated or asimilated into other more powerfull groups and some have gotten more powerfull than ever before..
Other groups that might appear would be extreme-religious groups,right or left wing fanatics,extreme PETA groups,militant greenpeace groups and the like..+ bands of various military,government,police,national guards,mercs,,,the list goes on
I guess with the fall of central government "the human condition" will truly present itself hehe
