Answering the questions following his mysterious blog post from a few days back, George R.R. Martin has revealed that Fire and Blood is closer to publication than many thought. A book focused on the history of the Targaryens in Westeros, drawn in large part from material originally created for The World of Ice and Fire but which was largely redacted or severely compressed from that book, the amount of material is so sizable that it will appear in two volumes.
Per George:
No publication date has been set yet, but it’s likely that we will get the first volume of FIRE AND BLOOD out in late 2018 or early 2019. The second volume, which will carry the history from Aegon III up to Robert’s Rebellion, is largely unwritten, so that one will be a few more years in coming.
And for those who wonder about the state of The Winds of Winter...:
Whether WINDS or the first volume of FIRE AND BLOOD will be the first to hit the bookstores is hard to say at this juncture, but I do think you will have a Westeros book from me in 2018… and who knows, maybe two. A boy can dream…