Sex sells and always has in the world of erotic fiction. But how will it fare once the roaring, gushing, all-consuming passion for E.L. James’ Fifty Shades of Grey is finally spent?

On Saturday, a lively group of writers and editors on a Miami Book Fair International panel aim to explore the state of the genre, which appears to be more fertile than ever.

Erotic fiction has been around forever, though if you haven’t paid attention you could be forgiven for presuming it surfaced just last spring, when Random House imprint Vintage Books published the 5 0 Shades trilogy and all bondage broke loose. The novels, about the inexperienced Anastasia Steele and her billionaire, S&M-obsessed paramour Christian Grey, have sold 35 million copies in the United States in all formats — with worldwide sales of more than 50 million, according to Russell Perrault, vice president and director of publicity for Vintage.

The novels meld classic romantic formula — James was inspired by the fan fiction she wrote about Twilight — with explicit BDSM (that’s bondage/discipline/sadism/masochism to you), a clearly potent blend.

“At another time in America, ‘erotica’ meant Henry Miller or Story of O, sexually frank literary fiction that changed U.S. obscenity laws forever,” author and activist Susie Bright said via email; she’ll be part of the book fair panel. “It was a First Amendment and intellectual breakthrough as well as steamy nostalgia. Shades of Grey by comparison is a triumph of ebook marketing — it’s a business story, the killer ap that happened to be a book. Shades also represents the dominance of fan fiction a la Twilight and the romance genre’s complete dedication to erotic storytelling. Romance for years has been as triple X as you can imagine, but it was the nice girls’ ... secret. No one’s pretending anymore.”

Indeed they are not. These days you can find an erotic fiction section in Target and prominent displays of 50 Shades knockoffs in airports across the country, though ebooks have made things easier for shy readers embarrassed to buy explicit titles. Heated fans argue all over the Internet about who should play Christian Grey in the upcoming film. Parodies are popping up, like Fifty Shames of Earl Grey by Fanny Merkin and Andrew Shaffer. James is mulling a fourth book, and copycats are no doubt cashing in on the wave. Meanwhile, longtime erotica writers — while pleased with the media attention — wonder if new readers will find their way to and stick with other, quality work.

For publishers, the success of 50 Shades has been a boon — according to Brenda Knight, associate publisher of Cleis Press, which has been publishing erotica for 33 years.

“We’ve seen an amazing thing happen,” Knight says. “We started hearing about 50 Shades last March. By May, Fifty Shades fever had kicked in. ... It really helped mainstream erotica. I think our sales went up something like 30 percent. It’s settling back down now, but when a fourth book comes out, we hope it happens all over again.”

Romance publisher Harlequin launched the erotic imprint Spice in 2006 (it has since been rolled into Harlequin’s other imprints), and Susan Swinwood, senior editor for the imprint Mira, says the phenomenon “kind of left you scratching your head.”