I've heard tablets will eventually replace all portable devices such as, ebooks, phones and computers and we'll all be surfing, reading, calling on our tablets on the cloud. I see at least 3 problems with that:
An all purpose cloud connected tablet would be too big if used as a reader for me. Yet still too small to be used as my main computer, while I find it cute to see people surfing on their I-pad sized tablets, I don't like such a small screen to display web pages (as my main computer I mean). I won't even get into the right size debate when used as a phone.
To make it short, If I liked to read on a computer type of screen, I'd have the I-pad. I love e-ink because it is easy on the eyes to use for hours on end.
Again a decent size for it to be called one's main computer would make it ipso facto not as portal as an e-reader or a phone. While we have some portability with our laptops, we don't carry them around everywhere as easily as we do our phones, do we.
For those reasons I don't think that e-books will come to a generational end any time soon. They will evolve yes but the fact that we need something that fits in our pocket will not change IMO.