I wonder just how many library books are read on eBook readers? I suspect it is a VERY small percentage compared to paid and free eBooks. Most libraries don't have much of an eBook selection and many have none. I checked into the selection several months ago and found nothing I cared to read. Polls that have been conducted in these forums tend to show a huge disappointment in the availability (or unavailability) of library eBooks.
My guess is that library eBooks will have little impact on the sales of readers capable of reading them.