Millions of books are being replaced; each parish must buy its own. (What becomes of the old books? The U.S. Conference of Catholic Bishops recommends burying them on church grounds or in a parish cemetary.)The statement of the U.S. Bishops' Conference also suggests ritualizing the disposal process by saying a blessing when retiring the outdated books. It notes that because books used in the liturgy are blessed, they should be treated "with respect."
The collection of essays edited by Kristina Myrvold, "Death of Sacred Texts," surveys how various religious traditions handle this problem. Dorina Miller Parmenter's essay in that collection points out that Christian traditions tend to have fewer mandates regarding the disposal of sacred books than some other religions, but that lay Christians often voice discomfort at simply trashing or recycling Bibles or other sacred texts. The bishops were responding to queries motivated by such concerns when they issued these instructions.
This is not, however, just a religious concern. Unease over book destruction or disposal is widespread Sacred texts only provide more focused examples of a broader concern, as several previous posts (here, here, and here, as well as the entries under the label "disposal" at left) have observed.