This is a reply to my post below about media and context and books but I can't put links in the reply box and I wanted to attract your attention to these two pieces about the future of books.
I had another thought on why the book can't be allowed to be replaced. One of the biggest problems facing computer scientists is the issue of data retrieval and obsolete hardware. Already, there are computers from the seventies that are unreadable because we have no way of accessing their hard drives through a computing language no one knows any more. (Who out there still uses Basic? Remember that?)
An allegory would be the Dead Sea Scrolls. These papyrus texts were lost for 1800 years. When discovered scholars instantly knew how to decipher them and we now have their knowledge. Imagine in a thousand years after the next ice age a shepherd boy discovers an imac in a cave (it could happen) Assuming the components hadn't rotted/oxidised/melted the people of the future now have access to the computers hard drive and its 40 gb of fabulous knowledge. However, having no way of actually reading whats on the hard drive the people of the future re-invent the frisbee.
The point is that in a thousand years they would have to re-invent the imac to be able to read it. We didn't have to re-invent paper to read the Dead Sea Scrolls. It is simply impossible to invent a computer and software language that will last for an eternity. So, if we want the sum of human knowledge to be passed down the generations then we simply have to keep the printed word. Full stop.