One has to wonder if books will eventually be available on sites like a (fictitious at this point) “youbook.com” wherein one might download the first chapter for free and pay only for downloads of additional chapters.
Baen Books (sci-fi publisher) already has the first few chapters of each book on its website for free. If you like'em, buy the book (either paper or e-book). And no DRM (digital rights management) bullbleep, either. Baen ebooks are avaialbe in many formats, including epub.