What if, like the second best selling book ever, it takes almost a decade for the book to begin selling well? If books can cease to produce money just as their popularity begins to crest, then I imagine publishers will be less eager to publish things that aren't likely to be immediate hits. I have the impression that many of the books which our culture treasures weren't immediate hits.
The thing is that books DON'T cease to produce money when copyright lapses, the copyright owner just loses their exclusive monopoly on the work. If they continue to offer the most compelling reproductions of the work (in the case of a book: form factor, bindings, indices, appendices, cross-references, etc.), they will continue to make money. The competition would greatly enrich the consumer experience.
