Short Roy Tennant LJ blog
post on the very same topic:
Libraries, of course, are caught in the cross-fire. Collections of VHS tapes will not be worth transferring to a new format. The best that libraries can do is to start buying content on the latest format and slowly phase out the older formats as demand declines. The problem with this, of course, is that libraries may actually have to buy the very same content all over again but in a new format. And how long will Blu-Ray last until something better comes along? There must be a better way.
(http://www.libraryjournal.com/blog/1090000309/post/1740037574.html)