[ghaff]

It's a complicated question.

On the one hand, barring natural disaster/fire/water leaks/etc., your library book will last a good long time--at least until the library gets rid of it because they need the space and no one's checked it out recently. On the other hand, even with inter-library loan, it's not super-accessible especially if it's in, say, a private university library. And if something does happen to it, it's gone.

On the other hand, a single digital copy won't last as long. But subject to a lot of factors and caveats, copies of that digital artifact can last indefinitely.

[ivankolev]

Yes, trade-offs all the way down :) Physical damage of the nature you described affects many forms of digital storage too, though I doubt vermins will find them very palatable. And there could be many copies of a book, to your second point. There is also the question of the specialized equipment needed to read the digital media. As I said, trade offs. I try to maintain a personal book library just because I was an avid reader growing up, in the pre-internet days, and I don't want to see the future generations go pure digital, but maybe it is inevitable.