In my books, I've predicted...
Oh, wait, that hasn't happened yet.
But in another book, I predicted--
Hold on. It's 2011, right? Not yet either.
I did come up with...
No; that was Lester Dent.
Oh, I know! There was--
Wait. The real thing was even smaller.
Ah... I predicted the smartphone.
(Wait,
what?
Really?!? When?)
Sigh... yeah, it's tricky predicting the future, and I can't think of too many books that have done it accurately, if at all. But the real value of the concept depicted in SF is to highlight the aspects of our use of science and technology that are most important to us at the time; for instance, our depictions of living arrangements in the future, whether they are single family homes in the technology-tamed suburbs, huge Arcocities housing all of humanity apart from the ravaged countryside, or <gratuitousPlug>
city-satellites in space</gratuitousPlug>.
Another useful barometer such books provide is whether we perceive of those developments to be good or bad things: Supercities, for instance, have been perceived at one time as a triumph of human engineering, and at others an attack on Nature. Space colonization has been called Manifest Destiny, and abandonment of Mother Earth.