Witold Rybczynski asks that question in response to the possible demolition of Washington's Martin Luther King Jr. Library, the only one designed by Ludwig Mies van der Rohe. A task force calls it "an outmoded structure erected long before the advent of the digital world." Rybczynski writes in Slate:
Historic preservation aside, this raises an interesting question: What sort of public library does the "digital world" of Google, Wikipedia, and Kindle require?
The answer appears to be that nobody knows. Robert Stern Retro seems to be all the rage, trying to recreate the Reading Room of the New York Public Library. Rem Koolhaas' Seattle library is "a single, freewheeling space inside a giant, multilevel greenhouse. This is the library conceived as a drop-in center, filled with computer terminals, magazine and newspaper racks, lots of comfortable seats, and, yes, even bookshelves."
It is too early to know the answer to the question of what libraries will be in twenty years, but Rybczynski concludes: "in its mutating role as urban hangout, meeting place, and arbiter of information, the public library seems far from spent. This has less to do with the digital world—or the digital word—than with the age-old need for human contact." ::Slate