Believe it or not, I like this use of DRM as long as there is a reasonable usage period. I hope my library does this sort of thing. For a library book or audiobook, I expect to only use it for a period of time, so this expiration business is the way it should work.
Until then, did you know that in the US, IggleVideo (at many Giant Eagle grocery stores) and Cracker Barrel (in the coutry store) you can rent audiobooks? In the case of Cracker Barrel, you can even return the book at another location!
And there's always Audible.com for a premium solution.