The unthinkable is thinkable. No: likely.
I find it expressed in various passages of Scripture that the fact that God knows things while in a state of possibility, when their existence belongs to the future, does not change the nature of the possible in any way; that nature remains unchanged; and the knowledge of the realisation of one of several possibilities does not yet effect that realisation. This is likewise one of the fundamental principles of the Law of Moses concerning which there is no doubt nor any dispute.
Remember, the goal of structured futures thinking is to come up with a picture of possible futures that will help to inform strategic decisions.
No, I think the future of humanity will be like the past, we'll do what we've always done and there will still be human beings. Granted, there will always be people doing something different and there are a lot of possibilities.
Our thesis is that symbols and myths are an expression of man's unique self-consciousness, his capacity to transcend the immediate concrete situation and see his life in terms of 'the possible,' and that this capacity is one aspect of his experiencing himself as a being having a world.
Speculative fiction encompasses that which we could actually do. Sci-fi is that which we're probably not going to see.
All imaginable futures are not equally possible.
The only science fiction I have written is Fahrenheit 451. It's the art of the possible. Science fiction is the art of the possible. It could happen. It has happened.
We need a multiplicity of visions, dreams and prophecies - images of potential tomorrows.
What SF can do better than anything else is show us the range of our possible futures, and what we can do to realize the good ones and avoid the nasty ones.