The article you linked to is complete crap. It extropolates 40 years into the future but makes the same mistake as all end-of-days fear mongerers: he assumes present day technology.

If oil ran out tommorow we certainly would not fall into another dark age. Alternative energy technology already exists, a major crisis and the economics of scale that would be created for alternative energy technology would assure that. The fact is, though, that oil is not going to run out anytime soon (at least another 40 years). By that time we'll be generating our energy from nuclear or renewable sources and replacing the natural energy storage method (oil) with a newly engineered storage method (fuel cells).

How long have men been predicting their own demise? Has not every one of them been proved wrong?

I'm wondering when Transhumanists who expect to "live forever" are going to pick up on the fact that the developed world's energy infrastructure is rapidly deteriorating because of the decline in per capita energy consumption since the late 1970's. This trend could lead to permanent blackouts in about a decade. We've already seen some previews of a catastrophic Final Blackout this year in North America and Europe, and just the other day the British press warned that the U.K. is vulnerable to massive power failures this winter.

Some scientists have already found the key to immortality – but do you honestly think they are going to share their discoveries with the rest of mankind – especially in this day and age where everything is focused on greed and destruction? I think not; it is best that the majority of the human species becomes annihilated before such discoveries surface.

I'm 23. I may die, but I'm not sure.

The amount of technological progress that the species will make over the next century will be absolutely mind boggling. I think that its extremely shortsighted to believe that the human lifespan will still be a maximum of 120 years at the end of this century. It might, but to dismiss it because no one has ever lived more than 120 years (or therabout), its to deny that progress will be made. The theoretical limitations of technology are infinite, to deny that this technology might be used to increase our lifespan is ignorant in the extreme.