the other possibility might be that book publishers marry themselves to apple and or amazon, and use their tight controls over content distribution. although, it might end up eliminating some fair-use rights, but something like that has already been played out before.

ipad/kindle etc point a way to bring back the copyright controls into the architecture of how people read books. i think lawrence-lessig talked about this in the "code and other laws of cyberspace". building tight copyright controls into a closed device is much simpler than a general purpose computer. sufficiently motivated folks can crack the ipad controls, but it is an open question if it can be managed while still letting ipad access the various stores that provide the content.