"Then there's prose SF, which is basically dying... there are still fine novels being written that you could classify as SF, just as there were before Goddard and Tsiolkovsy - but, just as in those days, they are not generally shelved in a special section of the bookstore called 'SF'."
Admittedly, this is hardly the first time I've heard this sort of argument. My old roommate in Toronto would bring it up fairly frequently, arguing that our generation was suspicious of the traditional SF tropes of galloping science solving social ills, and that a dissatisfaction with the idea of science in general was one of the factors pushing the growth in fantasy-focused literature. While what may charitably be described as "science fiction" does still bring in the bucks in the movie theatres, I'll readily admit that when it comes to what you'll find between two covers, it's not as sharp as it must have been back in the day.
Understandably, though. You use a knife enough times, it tends to get dull. Science fiction authors have been digging down into the mines of tomorrow for more than eighty years now, and even if most of the early work was crazy pulp about supertechnology and planetary invasions - so, really, not too different from a lot of the stuff you'd find on the shelves today - there were thoughtful gems from the start, even amid things like "Revolt of the Ants."
A significant fraction of the works on this shelf may have already been almost completely forgotten!
I know I'm biased as hell, but even so I don't think "dying" is an entirely appropriate way to describe the state of written science fiction today. For me, it feels like we're more in a winter of sorts - sure, the sun is still shining, but no longer is it the summer blaze of the 1960s and 1970s, when Everyone Knew that moon bases and space colonies were Definitely Right Around the Corner. We've finally reached the point where a lot of things featured in SF of older days should be coming to pass... except it isn't. If SF was a roadmap to the future we've finally pulled into the parking lot, but someone's taken down all the signs pointing us to the entrance.
As for prose SF? To be honest, it depends on the medium. For decades, it's been dominated by novels; novels were the way authors tended to get their stories out there, novels were the way that the lion's share of authors became known. Perhaps it's that aspect of the genre that's dying instead. I have to wonder if we're not becoming primed for a new age of short stories - brief, comparatively simple things that still have the capacity to touch, to affect, and to be read while riding the train to work. That's one reason why I don't read novels as much now as I used to, I think - I prefer to devour in a single sitting, if at all possible.
Of course, seeing as how I am primarily a short story author, I am likewise biased as hell here. Even so, I wouldn't mind a new age of short stories. There's something about a magazine or anthology that's worthwhile - a multiplicity of viewpoints and ideas, small and nimble and yet still effective. Science fiction has been around for eighty years - I don't think it's on death's door. What it needs is new viewpoints and new voices, and a new way of reaching the world.