There might just be a little more for Game of Thrones fans to read.
While answering fan questions on Suvudu Universe, George R.R. Martin's editor Anne Lesley Groell wondered if there might be more than seven books in Martin's A Song of Ice and Fire series:
I begin to wonder—though 7 is what we currently have under contract. I remember when he called me, years and years back, to confess that his little trilogy was…well…no longer a trilogy. He predicted four books. I said Seven Books for Seven Kingdoms. Then he said five books. I said Seven Books for Seven Kingdoms. Then he went to six. I said… Well, you get it. Finally, we were on the same page. Seven Books for Seven Kingdoms. Good. Only, as I recently learned while editing THE WORLD OF ICE AND FIRE (another awesome thing you must buy when it comes out!), there are really technically eight kingdoms, all having to do with who has annexed what when Aegon the Conqueror landed in Westeros. So, maybe eight books for Seven Kingdoms would be okay. Also, he has promised me that, when he finally wraps this great beast us, I can publish the five page letter outlining the bare bones of the "trilogy."
Groell also said that even she doesn't know when the sixth book will come out. "When I have a date, you will have a date," she said. "All I can say is that George is hard at work, and we hope to have it reasonably soon. I currently have 168 pages that he submitted back in February 2013 in order to receive a contracted payment, but I know more exists, because he keeps talking about chapter he hasn't yet sent me."
The fifth book in Martin's series, A Dance With Dragons, landed at No. 1 on USA TODAY's Best-Selling Books List in 2011. Martin might want to write more quickly: the HBO show based on the series is quickly catching up with him.