Chess eBooks is the future, for many reasons.
It's economically easier to update them.
It's easier to update them when errors has been found in a previous edition.
It's easier to update a opening eBook than a opening paper book.
It's easier to travel with hundreds eBooks than hundreds paper books.
You don't need to have so many bookshelves.
And a opening eBook should be updated once a year (at least in popular opening variations), and not every 5-10 years as normal with paper books. Tournament players don't like to wait 5-10 years on a updated opening book about the Sicilian Najdorf, Sicilian Dragon, French, Ruy Lopez, Slav, Grünfeld, Queen's Indian, English etc.
Since eBooks are cheaper to produce, do not require paper and ink, and have no shipping charges, eBooks should be cheaper for readers to buy. Right now, some publishers make eBooks just as expensive as paper books, but this will change in time.