In the age of the Kindle and the iPad, the concept of traditional book stores closing these days is becoming commonplace. I fought this trend in my own mind because as much of a digital person that I am, I enjoy the physical nature of a book. Traditional books speak to my sentimental side too — I can remember my grandparents having a marvelous collection of titles that they had accumulated through the years. As a kid, I didn’t know what most of the contents were, but it spurred the imagination to see so many books lined up high and back-to-back against a wall.

So when a flagship book store closes like the one Borders Books and Music had across from Water Tower Place on 830 N. Michigan Ave., it serves as the official signal that, like it or not, the e-reader has won. Think about what a store like this had going for it: A prime location on the Magnificent Mile. Close proximity to shopping and restaurants. 3 floors of regular activity.

And yet, even here, it wasn’t enough. Soon, I believe we’ll be looking at book stores the same way we look at the occasional record store these days – “wow, they still have these things? Who goes there?”

In other words, if you think the Kindle and iPad are popular now, you ain’t seen nothin’ yet. Of course people have them. But I’m talking about a different tier than where we are now. You know how every 3rd person on the street has a smartphone in their possession? This level of mainstream adoption of the e-reader isn’t far behind. The way it is unthinkable for most of us to not have an iPhone, Android, etc. in this day and age will be the way we view the concept of not having an e-reader. Laptops and smartphones will be more important to our daily lives and for connecting with others, but gaining information for news and entertainment purposes in a format that is the most akin to a book or magazine will rank high on our priority list too.

For marketers, it represents a potential new opportunity to a degree. I don’t know how receptive someone might be when immersed in an e-book to suddenly see an ad float nearby but some may put up with it to pay less (not unlike other models where you need to pay extra for ad-free). Personally, I’m skeptical until I see numbers that this will lead to converted sales, but if the goal is more brand awareness without annoyance, it may not be a bad route to at least evaluate in the right circumstances.

What I’m interested in is, now that we’re being pushed toward this medium, how will different audience segments adapt to e-readership and what does it mean for even greater interaction electronically. For example, what does it mean for awareness of transit advertising when even more commuter eyeballs within that bus or train are drawn to Kindles and iPads? Does the age ceiling of the audience raise higher and become older than ever?

In a world without Borders or Barnes & Noble or Virgin Megastores (A library? What’s that?), the choices we’ve had as far as physical options for books are falling like dominoes. The challenge from here for agencies and marketers will be how to engage in sophisticated media planning when the media for the masses we’ve known is looking ever more like a Personal Cloud of media controlled by the consumer. The noise you heard from Michigan Avenue of the doors locking at Borders is just one more pillar to fall in that direction. But as I’ve said before with newspapers, the desire for news and entertainment didn’t die. The format for how people desired the content merely evolved. There’s no point in fighting this evolution either. But make no mistake as a result of this one and other evolutions like it: Marketers need the technological tools for understanding media consumption and shifts in audience behavior to be more advanced than they’ve ever, ever been.