I think the SV community touched on some elements of this when we were discussing Is fantasy easier to write than science fiction?
It seems that for many of the authors, it comes down to what the definition of Science Fiction is. For most of them it comes down to either a view through their own sub-genre, as The Master commented, or through the eye of someone who's actually read a lot of Science Fiction.
Far off planets, future timelines, and three-eyed aliens don't necessarily make something Science Fiction. However, to your average Joe, that IS Science Fiction. You have to have that stuff in Science Fiction, right?
Most of the authors don't seem to be concerned with the death of Science Fiction as much as the death of GOOD Science Fiction. I think Ursula K Le Guin's comment that "much science fiction is really fantasy in a space suit," seems to resonate among all the authors and myself included. While there is room for the space opera sub genre, there's the fear that it will take over to the point that that's all is left.
If you break it down, you've got science
. A fictional tale that science plays a part in the telling of. Good Science Fiction doesn't need to be set in the future with aliens. Stephen Baxter commented that "...science fiction has - rarely - been about the prediction of a definite future, more about the anxieties and dreams of the present in which it is written" and IMO that's at the core of what good Science Fiction is. Looking at a certain element of today and if not taking it to an extreme, in say a post-apocolyptic nuclear war setting, at least using it as the focus of the story.
Science Fiction is fueled by science. As long as science keeps advancing, keeps coming up with new ideas, Science Fiction will always be there. The focus of popularity in the genre may shift from one sub-genre to another, but I don't see Science Fiction ever dying. GOOD Science Fiction...well...it'll always survive in certain mediums. btw, I loved Margaret Atwood's intro paragraph...Is science fiction going out of date? No point asking me - I'm too old - so I had a talk with Randy-at-the-bank, who looks to me to be about 25. (That may mean he's 35: as you get older the young look younger, just as when you're young the old look older. Time is relative. I know that from reading sci-fi.) I knew he was a sci-fi fan because he said he liked Oryx and Crake
(Margaret's latest book.) So as he was setting loose the key I had somehow got stuck in my own safety-deposit box, I asked him what he thought.