While I think intelligent predictions of which books people will like will become more sophisticated over time, I think in the future the social element of reading will be a huge factor in which books people choose. People will form niche communities around their particular literary tastes, and use those communities to find new books. This is a good example of the long tail, where with the growth of Web 2.0 technologies, people can now find like-minded individuals across the world for any set of tastes and preferences.