Yes, I do believe that books could one day be a form of currency, With technology like kindle one the rise, people who buy books are becoming rare. I believe that people will start trading well like books to buy other merchandise. I see it happen every day between family and friends and I know one day this will be reality.
Well, just about anything can be currency, so why not day books? The most popular form of currency in developed nations is currency, which is basically the government saying "this paper with funny designs printed on it has value because we say so." So if you can get people to believe it and back it, then go for it.
I think anything could be a form of currency if you can find enough people to accept it in exchange for products and services, we have seen throughout history different forms of objets and items being used as currency in one form or another, as long as people are willing to transact in it then it can be considered a currency.
I think the paper version of books are really getting a run for their money. I think in the future books will be printed far less than they have been in the past. In the future, this will make paper books very rare and people will seek to collect these old wonders. Their value will rise, but it is unlikely that they will become a form of currency.
I do not believe that books willl ever be currency. First of all, the idea that books can ever be currency isn't a logical one. Books can different in subject material and topics. It would not makes sense to use such a thing as currency. And second, books would be difficult to carry around.