Can Science Fiction Survive the Future?

I’ve been thinking a lot about this question lately.  It has nothing to do with the publishing industry, sales, or anything like that (at least, not directly).  What I’m really curious about is the ability for science fiction to be science fiction as time progresses:  will we always have science fiction, or will it die because the genre ceases to have a setting which sets it apart from the present enough to make it recognizable as a distinct genre?  Since I don’t consider alternate history to be science fiction (it fits in its own genre, in my mind), there is a very real possibility that our future will make setting SF in a radically different environment (a defamiliarized zone, to link this whole discussion to Fredric Jameson) near impossible.

Or will it?  Would we still consider books about alien encounters science fiction even if the means to travel between worlds becomes relatively simple?  Or would such stories become fantasies?

When I first began thinking about this question, it occurred to me that many of the definitions we use to describe SF, even in a fairly general sense — such as Darko Suvin’s “cognitive estrangement” or Fredric Jameson’s own manipulation of that concept — become obsolete as the present encroaches on the allegorical past/present/future commonly associated with SF.  How can something be SF if it represents our immediate reality?  That, to me, seems more like mimetic/realistic fiction than anything else.  How do we define a genre like “SF” when it is indistinguishable from realistic fiction?

These are the kinds of questions I’m curious about.  Maybe you all will join in and give me your thoughts.  Comment away.