The whole concept of "subcultures" when it comes to fiction is inaccurate, though, because contemporary literary fiction is about as sub- to a culture as it's possible to get without hitting the ocean floor. Start talking about audience sizes, and the supposed subcultures don't seem so small anymore, unless you're comparing them to Hollywood, which is one of the only real general interest entities functioning in the U.S. anymore (probably to its detriment, but that's another subject altogether).
As forms of distribution change because of technology, then cultures and how we define them change, too. We can all get more specific stuff more easily than it could be gotten, say, thirty years ago. It's impossible to get any sense of what's going on with short fiction if you aren't also at least partially aware of things like the "long tail" concept:
Unlimited selection is revealing truths about what consumers want and how they want to get it in service after service, from DVDs at Netflix to music videos on Yahoo! Launch to songs in the iTunes Music Store and Rhapsody. People are going deep into the catalog, down the long, long list of available titles, far past what's available at Blockbuster Video, Tower Records, and Barnes & Noble. And the more they find, the more they like. As they wander further from the beaten path, they discover their taste is not as mainstream as they thought (or as they had been led to believe by marketing, a lack of alternatives, and a hit-driven culture).I'm not any sort of economist, so if this whole idea is full of horse effluent, let me know, but it makes intuitive sense to me, and it seems to be what's happening with short fiction, and one reason why "general interest" is becoming a contradiction rather than the convenience it's been until now.
An analysis of the sales data and trends from these services and others like them shows that the emerging digital entertainment economy is going to be radically different from today's mass market. If the 20th- century entertainment industry was about hits, the 21st will be equally about misses.
It's going to be more and more difficult for some places to maintain their audiences without radical change, but there are other markets that are probably capable of surviving just fine, and even prospering, with only an occasional tweak. The short story is not dead in American culture -- various Best of the Year anthologies, whether specific to one genre or more general, don't sell too badly, suggesting that what the contemporary audience wants is not so much a continual blitz of monthly fiction, but fiction in portable chunks. The monthly and even weekly delivery of fiction may get taken over primarily by internet publishers, while print publishers find more success with less-frequent publications. As someone who has an awful lot of magazines, I can't say I mind the idea of most magazines becoming internet publications, because, frankly, they take up less room, and if I happen to forget an issue, I can go back through the online archives rather than digging through boxes. If I can zoom in with Google, I like as long a tail as possible, but prefer a much shorter one when it's stored at home, wriggling over shelves and the floor.
Perhaps the real future is one that's more like what's done by Pindeldyboz, Rain Taxi, and various other magazines that have separate, complementary print and web editions. Maybe it's more like what Strange Horizons, Infinity Plus, and Fantastic Metropolis have done: web content primarily, with an occasional print anthology.
Short fiction writers may not be able to make the kind of money that F. Scott Fitzgerald got from The Saturday Evening Post (reportedly $4000, or, according to the Inflation Calculator, about $43,200 today), and it's certainly unfortunate that a high-paying market like The Atlantic is cutting down on its already-marginal supply of stories, but there are plenty of readers and writers of short fiction out there today, and a magnificent diversity of approaches and styles. With any luck, as markets for and distributors of short fiction find ways to adapt to changing circumstances, more people, rather than fewer, will make short stories a regular part of their reading life.