I have a printed book that's the same age as the U.S. constitution (now 231 years) and another printed book that's a few decades older (293 years), both of which are still completely legible. "Decades" feels like a big understatement to me. :-)
We mostly think of paper as a poor archival medium because of a few decades, mainly at the end of the 19th century and the first half of the 20th century, when high-acid wood pulp paper was very widely used. (Newspapers are also sometimes printed on cheap acidic newsprint.) Acidic paper can become brittle within 20 years or so, or in any case much less than a century, although this also depends on many other factors. But both before and after this period, many books were printed on acid-free paper, and these are likely to survive for centuries, even with occasional use. The observations about paper's longevity in, for instance, Nicholson Baker's polemical Double Fold, tallies well with my experience as the son of a bookdealer. My father routinely sells books that are over a century old to people who fully expect to read them.
And I remember visiting an antiquarian book fair where a first folio Shakespeare was for sale for millions of dollars. It was still possible to turn the pages with no damage and all the printing was completely legible, even though the book was already 380 years old or so.
Books on low-acid paper are really a very durable technology when treated with respect.