You know, here in Russia (yes, I know that I'm always pushing towards Russian things
) there's a joke:
One (western, middle east, eastern, insert your own) company has bought from Russians the schematics for the new superb helicopter. The schematics were delivered, and the engineers and technicians began their work to recreate the design and build the final machine. Some time has passed, and Russians get a letter from the engineers: "You know, guys, we followed the schematics precisely, we've considered all notes and precautions, we used all the mentioned materials, but... In the end, we've built a STEAM LOCOMOTIVE!". "This just cannot be," - was the answer. Please, follow all directions carefully, and you'll achieve the desired result. Another bunch of time passed and the Russians get the similar question again: "Guys, what the frag? We're doing all as prescribed, but we're still getting steam locomotive instead of helicopter!". After continuous arguments one of Russian engineers goes to customer's country, gets to the development site and observes the work. After a while, he shouts "Stop all what you're doing". He gets the specs, calls the Engineer-in-charge, and puts his finger in the docs, where there's a single note on a very first page: "Before assembly, all the parts must be thoroughly worked on with the rasp."
In the end, the helicopter was assembled.
What I'm trying to say is not that Russians are so cool, I'm trying to say that a man, a Human, is a very, VERY creative and unpredictable (though often strange) being. One man may be weak or strong, but a group will survive almost everything (in some cases even if the environment normally means certain death - as an example, remember what people had to face during the major-scale wars at least).
IMHO, the most 'realistic' picture of The Apocalypse is shown in Fallout game series. No mysterious catastrophes, no aliens, no Giant Meteors pushing a guy to the subway levels while leaving his dog-on-a-leash pretty alive. Just a perspective of things to come (and some of those things
will come as Earth isn't an eternal source of oil and gas). But even if something terrible happens, even if Nostradamus, Vanga and all others were right about the World coming to an end... the World (which is just a current set of boundaries with guns) may indeed, the Humans - no (which the same sci-fi Fallout series show as much). Humans can live in Antarctica, humans live in tropics, humans survive 50C heat and -40C cold, they grow plants where they normally won't grow, they breed animals that normally won't breed. Humans fly to space and live there... This line may be continued with much more examples.
In the end, what can wipe out the most adaptable living form known as per today? Perhaps, only if the Earth blows up before we can reach some environment-friendly world or convert an unfriendly one to friendly or convert ourselves to live in the unfriendly one (and the latter two seem more realistic to me). And the planets don't blow up on their own, at least that's a rule of Today.
Wow, that was a lot of writing