It's a physical world
Why do people still insist on limiting their technology by molding it into existing physical limitations?
The "Bonk to Buy" idea is quite nice. If you're in store it's a handy way to asses if a book is any good and then get it to your reader. But what if I don't have my device with me? if you plan it as your driving business model, I can't see it getting you too far. One of the main benefits of ebooks is I *don't* have to go to the store.
If you want to define your place in the future of ebooks, why not use your industry weight to provide DRM free books, at a better price than the opposition and with a better cut to the author? The sort of things readers want now.
On a side note, the Nook is a nice device. But unless you want to be a hardware vendor you're going to need add to that.