What InAudit.com calls, without irony, the “offline book industry” absorbed the news yesterday that Borders had filed for bankruptcy, the largest such filing in retail bookselling history.

In its court assisted reorganization the bookseller says plans to dispossess itself of almost one third of its retail stores (see the full list), three of them in New York City like this one, “no later than the end of April.” (In New York City, that means the stores at 576 Second Avenue / Kips Bay Plaza, 461 Park Avenue, and 100 Broadway / Wall Street.)

Beyond the loss of nearly 200 stores and an estimated 6000 jobs, as detailed in this Reuters wire story, the closings portend as yet unforeseeable repercussions for publishers and authors. Publishing and commerce are moving, in ever greater proportion, online — Amazon.com already owns the greatest share of the retail book market. Mike Shatzkin, who describes himself on his website as “Founder & CEO of The Idea Logical Company and a widely-acknowledged thought leader about digital change in the book publishing industry,” predicted in August of last year that “five years from now half of immersive reading — straight text novels and non-fiction — could have moved from paper to devices.”

What if he’s right?

As the share of the brick-and-mortar retail market erodes — stores close. As stores close, and as consumers desert printed books for digital formats, the market for printed books further contracts. (Some dispute the degree to which e-books contributed to Borders’s decline: Simba Information‘s Michael Norris writes that “there a lot of other factors involved that date back years before electronic books became trendy.”)

The end of mass production of printed books, however, does not depend on their complete abandonment in favor of e-readers. Printed books are costly to produce. Sooner, rather than later, the dwindling number of brick-and-mortar stores will not be buying enough “offline” books from publishers to justify the expense of printing, binding, and shipping them. Even after thirty years of intensive corporatization, trade publishing is not a business of fat margins. How many accounts can you lose and still a concoct a P&L that’s in the black? If all brick-and-mortar stores closed would Amazon‘s increased share of the market represent sufficient demand for printed books? It is probable that a shift of far less than the half Shatzkin predicts will be necessary to make book production prohibitively expensive.

Not everyone will lament Borders’ passing. The predatory expansion of the “superstore” model by Barnes & Noble and Borders was never welcomed by independent booksellers, many of whom could not compete when the national chains invaded their towns, or their blocks. More than 1,000 bookstores closed from 2000 through 2007 (according to this USA Today article).

In New York City, at least, one market category, the used-book store — the “secondary market” — is continuously reinvented. (“Secondary market” is a term introduced to me by Gary Indiana during a serendipitous encounter on the sidewalk in front of St. Mark’s Bookshop, as he rebuked me, a complete stranger who had just offered his unsolicited admiration, for buying a remainder copy of his novel, Depraved Indifference.)

Ursus Books and Prints, nearly forty years old, is a purveyor of art books, rare editions, and prints. Having spent the last two decades in the Carlyle Hotel, the store has relocated as of the first of this month to 699 Madison Avenue, the 3rd Floor, between 62nd and 63rd streets.

And Rob Warren, erstwhile owner of the late, lamented Skyline Books on 18th Street, was the subject of a New York Press feature last month, introducing his new venture, The Book Gallery, located within Garden District, Ltd., a flower shop, at 51 W. 28th Street. Like Ursus, Warren offers a collection primarily attractive to collectors of rarities. He says, “There are certainly books here that you’re not gonna find around town.”

And in the not too distant future, the books that you’re not gonna find around town will be the only books you’re gonna find.