This is a great article that dismantles many myths about e-books, copyright...
The one big issue though, which to me is crucial and unanswered for now is about pricing/revenue.
Sure iTunes is the biggest music store, but the music pie is shrinking in total $$ because of the much lower prices necessary to make iTunes work. The margins are squeezed and you need a very high in total volume increase to make up for that. Unlikely iTunes and the rest of digital stores will do that.
I am 99% sure that any move to pure digital will lead to similar revenue shrinking in books. People will buy and not pirate IF the price is right. And that will mean vastly lower prices that print equivalent, and the corresponding decrease in margins.
And books are not mass market items produced in a factory...