Earth: a "one-shot affair" for mankind

Studying recently several of the theories regarding our possible future(s) I came across this metaphorically named Olduvai theory by Dr. Richard Duncan

Even more than its contents and gloomy forecast, what I found very intriguing is the warning that stirred Dr. Duncan into researching his subject, which came from a rather provocative statement in a lecture by cosmologist Sir Fred Hoyle back in 1964:

It has often been said that, if the human species fails to make a go of it here on Earth, some other species will take over the running. In the sense of developing high intelligence this is not correct. We have, or soon will have, exhausted the necessary physical prerequisites so far as this planet is concerned. With coal gone, oil gone, high-grade metallic ores gone, no species however competent can make the long climb from primitive conditions to high-level technology. This is a one-shot affair. If we fail, this planetary system fails so far as intelligence is concerned. The same will be true of other planetary systems. On each of them there will be one chance, and one chance only. (Hoyle, 1964)

That being said, it seems the warning has been recently reiterated - last year, on quite a different note, but by a similar figure, the British physicist Stephen Hawking, who pointed out that as long as our race's fate is tied to this single planet we are on now, we risk extinction:
Hawking's warning

His list of possible disasters is rather short but to the point. I am hoping his words will be heard.
I would sign up for Alpha Centaury in a heartbeat - though, on second thought, I would wait to see my house finished first and my daughters in college second, but that's still only 18 years away. We'll see what's left of us then...

Did I inspire you to take that course in astrophysics or xenobiology that you were never tempted by?