I think if you're looking for technology to replace textbooks, you're thinking too narrowly. Technology can augment and supplement textbooks, and do many other things that textbooks can't.

And this leads to why so many technology projects fail (and not just in education)... because you first have to think about what you want to accomplish with it, how you intend to use it, and how you're going to support it. Those non-tech decisions then inform the technology choices... hardware, software, management, etc. Buying technology for technology's sake is fine for the home consumer, but at the scale of a school district, it's an opportunity for gross waste and mismanagement.