I know people who read copiously and rely on the public library. I know people who read all of the time and never set foot in the library. Some people buy on-island at Bestsellers. Others are avid on-line shoppers. Even those purchasing on-line frequent different sites-Amazon, B&N, Powell's, etc.
The recent news in the book world is that Borders may be shutting down (or being bought out by Barnes and Noble). Literary Agent Kristin Nelson does a good job analyzing the effect on small presses and authors here.
There's been a growing concern that books on paper are on their way out as technology changes. The decline in independent bookstores and now, possibly, a popular chain of bookstores seems to lend credence to this fear. Vanity presses and other self-publishing ventures, though, seem to be doing well at getting customers (people who want to publish), but of course less well at sales (people who read).
Change is constant. But I would miss Borders ( a place where I shop a lot on my infrequent trips stateside).