Jeff Harris provides a list of SpecNonFic:
HG Wells, Anticipations of the Reaction of Mechanical and Scientific Progress upon Human Life and Thought (coll of linked essays April-December 1901 Fortnightly Review; dated 1902 but 1901)
JD Bernal, The World, the Flesh and the Devil: An enquiry into the future of the three enemies of the rational soul (1929; 1969)
Michael Young, The Rise of the Meritocracy 1870-2033: An Essay on Education and Equality (1958)
IJ Good (ed), The Scientist Speculates: An anthology of partly-baked ideas (1962)
Arthur C Clarke, Profiles of the Future: Enquiry into the Limits of the Possible (1962)
Stanislaw Lem, Summa Technologicae (1964, 1974: 2012)
Nigel Calder (ed), The World in 1984, volumes one and two (1965)
Dr A R Martin, Project Daedalus: JBIS Supplement (1978)
Ed Regis, The Great Chicken Mambo and the Transhuman Condition:Science slightly over the edge (1990)
Damien Broderick, The Spike: Accelerating into the Unimaginable Future (1997; 2n ed. 2001)
David E H Jones, The Further Inventions of Daedalus: A Compendium of Plausible Schemes (1999)
Stephen Baxter, The Science of Avatar (2012)
Conway, J., C. M. Kosemen, & D Naish, All Yesterdays: Unique and Speculative Views of Dinosaurs and Other Prehistoric Animals. (Irregular Books, 2012)
Enrico Rodrigo, The Physics of Stargates: Parallel Universes, Time Travel, and the Enigma of Wormhole Physics (2010)
Lewis Dartnell, The Knowledge: How to Rebuild Our World from Scratch (2014)