I think the last 2 post make great points. If the survival scenario is personal as opposed to corporate (i.e., I'm SOL but everyone else is fine), then the urban survival skills required are those employed by the very poor and homeless today.

A bigger part of survival may include the change in mindset from absolute self reliance to asking for some help (friends & family, church programs, food banks, etc).
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Victory awaits him who has everything in order — luck, people call it. Defeat is certain for him who has neglected to take the necessary precautions in time; this is called bad luck. Roald Amundsen