By all accounts e-books are on the rise with readers such as the kindle gaining traction (at least in North America) in part due to the move to digital student textbooks. Saves weight, saves printing the damn things.
Do we then see the espresso book machine simply be another delivery mechanism, or indeed even have people turning up with e-books they've purchased already stored on an sd-card and having a printed version run off for them. And that means that the bookstore becomes a copy-shop (rather than a coffee shop). The implication being that people buy and download books almost exclusively online as already happens with music (eg iTunes) and then choose whether to burn it of CD etc.
(In this scenario online purchases of real books represents sort of halfway house until such times that everything is available digitally)
After all one of the things that makes books expensive is the distribution and shipping costs. If we get to a situation where people print only what they need to have in a portable non -electronic format - much in the way people print pdf's of journal articles they need to refer to, what will the book trade look like in five or six years time?