George R.R. Martin’s The World of Ice & Fire is an exhaustive history of Westeros, Essos, and the other lands that make up his A Song of Ice and Fire series, but you might be interested to learn that the book looks forward in time as well as backwards. Specifically, there’s a passage in the 300-page tome hinting at the terrifying Others’ endgame.
Hat-tip to io9 for pointing out an early chapter in the book, where Martin talks about the Long Night—the battle in which the Others attacked and rose wights before being beaten back by Ahor Ahai and his sword Lightbringer. Following the Battle for the Dawn, the Wall was erected across Westeros, keeping the Others and the White Walkers at bay.
However, in the discussion of the Long Night, Martin’s historian narrator gives an idea of what the world would look like if the Others were to succeed: very dark, very cold, very forever. It confirms what we’ve long thought about the Others—that while the assorted kingdoms are busy playing the game of thrones, these creatures are committed to freezing the world.
It’s an interesting perspective to carry into The Winds of Winter, as Martin has hinted that we will see more of the Others in the next book.