Being a science fiction writer means fielding a lot of questions about what the future is going to be like. It also means disappointing a lot of people when I tell them, "I don't know."
Not only do I not know, I don't even pretend to know. I mean, I can extrapolate from trends; I can guesstimate, I can figure out what cool toys I might love and give them to my made-up friends. I can research and see what the current state of technology is, and what's on the design board--but honestly, I'm not even slightly trying to predict the future.
(See? You're disappointed in me already. I can tell from here. But I am just trying to be honest.)
When I write, though, I'm not writing to an audience thirty years from now, or six hundred. I'm writing to an audience of today, with today's concerns and today's zeitgeist and today's worries in their heads.
Ahh, yes, today's worries. But many of those worries are universal--one might even say, human. And that stories that deal with those universal worries will remain fresh, or at least stand a better chance of it.
So I can't tell you what we'll be using for power technology in fifty years. I can't tell you if the Singularity will or will not happen, though I have my opinions (and I have opinions, too, about what the turn-of-the-millennium fascination with the idea reveals about our society, because projections tell you more about a person or a culture than just about anything else they do). I can't tell you whether we'll manage a credible approximation of A-life in my... er... lifetime.
But I can tell you how a human being reacts to change, and where we keep our ghosts, and how much work it is making ethical choices in an imperfect world. Because there are futurists and there are fictioneers, and we excel at different things.