Brilliant thread, folks! Coming to this late, I found many of my ideas and questions unfolding in the succession of posts. I was going to ask if a non-fiction, empirical foresight like Toffler's Future Shock," would be included in this equation; if Wells' The Island of Dr. Moreau, while concerned with experimental vivisection, was prophetic to some of today's new medical techniques (i.e. pig's hearts, etc.); and if a far leap of future prophecy, as in Heinlein's extra-dimensional space travel in The Time Tunnel is only a seeming leap until it's plausible, and then becomes a linear prediction.
However, the one direction of futurology not heavily mentioned is the sociofuturists, as in Orwell's 1984 (once regarded as science fiction.) Many of his "predictions" there are, alarmingly, already in place, and the vestiges of many others are increasingly appearing on the horizon. In like manner Huxley's Brave New World. And how would we categorize the allegorical teechnique of H.G. Wells' The Time Machine, where he depicts the Morlock society of the far future as a metaphor for the sad vulnerabilties of human nature? Is he saying human nature will never change, or just highlighting our present dilemma by using the future? And where does his vision of the machine, itself, fit into this discussion if it were possible? (in fact, the parallel of Wells and Huxley seems to be, "give people their 'paradise,' give people their 'soma', and you can do anything you want with them...in 1920 or in 4020). Then there is, for instance, the gracious and free-spirited sexual mores of Robert A. Heinlein's "Future History" (most notably in Time Enough for Love; the Notebooks of Lazarus Long), set in a far future world, but predictive of current trends in sociology?
Then there is also psycho-spiritual frontiers of C. J. Jung and others.
