Ebooks are great for the privileged middle and upper class. But thanks to DRM they lack the lend-ability and share-ability of real books, and they require a relatively expensive ebook reader. Even if libraries have the ability to lend every ebook ever published, it'll still require kids using the library to have a relatively expensive and fragile e-book reader. With real books, all they have to bring is an inquisitive mind.
With real books, even poor and disadvantaged children have access to books, not just through libraries, but also through borrowing, and sharing books from friends, relatives, neighbors, etc. And because most books are cheap to the point of damn near disposable in our society, most kids can count on getting gifts of books, hand-me-down used books, etc. Heck, it's pretty easy to scrape up an enough for a paperback on an allowance, lawn jobs, etc.
This worries me a lot. While I know that the circumstances I grew up in are very privileged compared to most of the world, we were poor by US standards. My family was often on some form of public assistance, and there's no way in hell I could have afforded a Kindle, Nook, etc. if such a thing had existed in those days. Growing up, the local public library was my teacher, my escape, my best friend. I'm saddens me to think kids in the near future may not have access to that same wonderful resource.