However, I referred to the set of genres overall. The book certainly is not dead. However, it takes up less of the "fine arts" market proportionally than it did a hundred years ago, and that's because other genres exist that allow people certain other freedoms.
It is easier to form a band now than it was a hundred years ago. A hundred years ago, it would have been extremely difficult, and there was less of a popular focus. There wasn't the insane level of attention to rock stars back then. And motion pictures didn't exist at all. Neither did animated pictures or video games.
This is applicable to the blogging situation as follows: 5 years ago, if you wanted to write online, a blog was the best way to go. Now? Not necessarily. Now you can Tweet if that serves your purpose, or you can maintain a videolog or a tumblelog. Many friends of mine abandoned their blogs for Tumblr for precisely that reason: it fits their needs. And yes, that's still technically a blog, but the format has changed. There are different rules and there is focus on different things. It's entirely different from maintaining a blog on Wordpress or Movable Type.
Nowadays, I don't see very many interesting posts from personal blogs. The blog posts I DO find interesting come from only a few places. The attention has changed to a variety of different mediums. Look at r/bestof/ on Reddit: suddenly, there are people who come to attention entirely through metaposting. Or, to take my example, I now link to my HN threads on my site and I've abandoned my blog for essays. It lets me build up a better relation between content that I write on the fly and content that builds up, that I slowly formulate and revise.
Of course the book isn't dead, or even dying, though in my opinion it's been 50 years since the last truly revolutionary piece of pure literature (Beckett). However, now if you've got a mind for expression there are more writing-based venues available. 100 years ago, you either wrote poetry, wrote novels, or wrote plays. Now you have lyric writing, film-writing, and game writing available. That fits what people want much more.
Look at the invention of science fiction: when movies first appeared, literature stopped dealing with sci-fi largely for several decades, because the minds that were attracted to sci-fi were attracted to cinema. The same thing is happening with video games right now: not all but many writers are joining on the science fiction game bandwagon. And so, if I were a game designer looking at a bunch of college students interested in science fiction, I might very well advise the students that novel writing might NOT be the best way to go on with sci-fi. Some people would ignore that and go on and try, but with so many other venues available, there's less of a pressure for books. That's how I see this article: it's an argument that a blog isn't necessary anymore. That doesn't mean people won't like it, and use it, but it means that blogging is no longer the primary source of content on the Internet.
I'm curious, what did you write about? Fiction/non-fiction? Still writing or just hacking?
Putting a book together at that age is a respectable achievement.
I still write, though I haven't written anything as ambitiously. My start-up is one that focuses on creative writers who want to learn to write at a more professional level, so it lets me get away with doing both. And I'll probably be writing something for NaNoWriMo in November: if I like that, I'll spend a little bit revising and seeing if any publishers are interested.
The two things go nicely together, because with literature you get used to putting things together haphazardly until they work: hacking gives you a more utilitarian approach to doing things. I find that when I'm in the middle of programming, I write better - if that makes any sense to you.