The reality of surviving long term solo for an extended period of time in the woods is mostly an unrealistic possibility. Most of us will have to survive some sort of temporary disruption of our normal way of life. It could be a tornado, earthquake, your car being broke down in the middle of no where, or being trapped in a airport for a few days. Whatever it maybe I think that those are the most likely things to prepare to survive. There are all kinds of tools that would be great to have and I have an EDC bag with some of my favorites. The most valuable thing though is mindset. I think that being a creative problem solver is the number one thing in any survival situation. I think that that is an attribute that most folks here have.
As far as gear in these urban situations:
-Your favorite multitool
-Flashlight (Not a million lumens we aren't landing a plane with it)
-A bit of food (powdered energy drink, nuts, hard candy protein bars)
-A way to carry / purify water (stainless steel water bottle gives you both)
-Basic first aid stuff (think blow out kit not bandaids)
-Bic lighter
-Bit of duct tape (for damn near everything)
-Heavy duty plastic zip loc bag (water proof your stuff)
-One large industrial plastic bag (shelter / poncho)
-A durable bag to carry this stuff around
-A set of picks (gets you more stuff in an emergency)
And finally my new most favorite EDC item a buff! Had no idea what this was until recently:
http://women.duluthtrading.com/store/product/head-buff-womens-merino-wool-buff-21547.aspxThis is the most useful bit of of clothing in my bag and it takes up zero space. Check out the diagram at the bottom of the page to see how it can be used.
Most importantly: KEEP IT LIGHT, KEEP IT WITH YOU.