https://www.cnet.com/news/george-r-r-martin-im-working-on-winds-of-winter/

He also apologized for calling the upcoming Game of Thrones prequel (Martin prefers to call it a "successor show") by his preferred title, The Long Night. 

HBO recently shared the news that Naomi Watts and Josh Whitehouse have been cast in the show, but while the network was careful to not give the prequel a title, Martin went ahead and called it The Long Night on his blog.