At least no one put dying while trapped in a metal box with salvation and air only an inch of unforgiving, unyielding steel away. Proves people read topics, at least.
I'm kind of with the poster who said that it varies from place to place. In the US, or similar countries, I could get behind the "losing all our technology" idea. We've come so very far with technology: to paraphrase the foreword to Kingdom Come (showing my comic book geek-ness, excuse me) today the average man is the superman. We can communicate over tremendous distances in an instant, traverse those distances in only slightly more time (comparative to how we managed them for millenia), we have ready access to any and every aspect of human comfort we could want (depending on personal economic status of course, so that last one's iffy). Within any of our lifetimes, the kind of things science fiction writers have been imagining for years will EXIST, and that's not even hypothesizing, it's fact.
But all of it is from technology. As a species, we've really not gone very far at all. Oh sure, we're universally taller and slightly more physically powerful, but when you get right down to it we are still killed just as easily by all the same old stuff, except for one or two diseases.
So what happens if the lights go out? Even better(worse), what happens if the lights go out permanently? How many people here can really claim to having survival training, or even any basic idea of what to do in order to live in such a situation? Yes, of course the number is low because of how far we raised ourselves up from that basic level, but that's the perverse beauty of it. Without all our shiny new toys, we're very nearly the same as we were millenia ago. Small, weak, and so very, very fragile.
Take that a step further: how many people reading remember how to use nothing but a library for a book report? Seems a daunting task even if you do, right?
Now turn it around. Remember that bit about science fiction becoming science fact? All the bad stuff applies too. Robots CAN really learn to lie, and develop self-serving personalities: this has been proven, if only on a simple level. People who know computers well enough can play with your life however they please, and may eventually be able to control you directly if cyborg-like technology (like the kind being developed to help blind people see) works out. Genetics is hurtling forward, and while pretty much everyone agrees creating a race of physically and mentally superior supermen is BAD, it's also pretty much inevitable that SOMEONE will do it. Nanotech is a real, steadily advancing technology and yes, they COULD go haywire and break down the entire planet to reconstruct it as themselves. Unless stopped by, say, an electromagnetic pulse, which would pretty much be scenario 1 all over again.
And that's just what we have and what is up-and-coming NOW. Assuming the concept of a technological singularity (In which technology cannot advance any further, as another poster used for an example) doesn't exist, that particular problem seems like it could only grow even further.
I'd say, (in the developed countries that have access to this kind of stuff, anyway) that is the fear of our generation. Our greatest strength is also our single most glaring weakness, and our most rapidly-growing if not-quite-omnipresent-yet threat.
Funny, I swear I heard a philosophy about that somewhere. Think it was a fighting cartoon of all things, hilariously enough.