I believe that even the pessimistic SF is quite likely a little too optimistic. If, as it seems likely, we run out of oil in the next few decades then every part of modern civilisation collapses. I suspect even the concept of SF will just become a distant memory. Not only will we have no energy, we'll have no food or any way to transport what food there is. What's worse is we'll then have a global population of 9 billion. Before oil the planet only used to be able to support 1-2 billion which means we'll likely have to loose 7 billion people. I'm guessing that won't be pretty.
The sad thing is that all this is likely to occur in my lifetime (just). In my old age I'm not expecting to be admiring the stars from the surface of Mars, I'm expecting I'll be foraging for a living here on Earth
