I've read a lot of books in the author's preferred formats (PDF and HTML5 websites), and my experience has been mixed.
PDFs are amazing for technical books, and I definitely prefer them for any kind of book with diagrams, code samples or pictures. However, every time I've tried to read fiction in PDF, it's been a miserable experience because support for reflowing/resizing text in PDFs is primitive or non-existent. The vast majority of PDFs are formatted for a fixed size, and are practically unreadable if you don't have at least a ~10 inch screen and an easy way to pan around. Mobi/ePub books avoid these problems, and are readable equally well on a 15" laptop or a 7" Kindle.
HTML5 is closer to the mark for fiction, because you can make an HTML5 website look great on virtually anything that has a modern browser. Here, the problem is that the nature of HTML5 makes it hard to produce a sellable product. When I buy a book, I want it in some kind of format that I can download and take with me, not a website that I need to authenticate to. Since the author says 5 years, I guess it's possible that the changes necessary will have occurred by then, but I think that it's more likely that e-books will be published in KF8/ePub3 and read on tablets and dedicated readers using specialized software, just like they are now.
PDFs are amazing for technical books, and I definitely prefer them for any kind of book with diagrams, code samples or pictures. However, every time I've tried to read fiction in PDF, it's been a miserable experience because support for reflowing/resizing text in PDFs is primitive or non-existent. The vast majority of PDFs are formatted for a fixed size, and are practically unreadable if you don't have at least a ~10 inch screen and an easy way to pan around. Mobi/ePub books avoid these problems, and are readable equally well on a 15" laptop or a 7" Kindle.
HTML5 is closer to the mark for fiction, because you can make an HTML5 website look great on virtually anything that has a modern browser. Here, the problem is that the nature of HTML5 makes it hard to produce a sellable product. When I buy a book, I want it in some kind of format that I can download and take with me, not a website that I need to authenticate to. Since the author says 5 years, I guess it's possible that the changes necessary will have occurred by then, but I think that it's more likely that e-books will be published in KF8/ePub3 and read on tablets and dedicated readers using specialized software, just like they are now.