Famous words of House Stark "winter is coming" are a constant reminder of what is in store for an unsuspecting Westeros. The words have also probably become a regular catchphrase for "A Song Of Ice And Fire's" author George R.R. Martin.
"Yes, 'The Winds Of Winter' is coming," Martin's reminder that a supposed book awaits not only his publisher, but also the HBO executives who will not give him room to write any more episodes, the fans who constantly question him on the release date, and possibly celebrity death pool bookmakers trying to understand everything about the series being completed, AV Club noted.
Now, there is certainty that the words can be supported with a definite date presumably. According to The Daily Dot, Alejo Cuervo, an editor working for the Spanish language publisher of ASOLAF, has been quoted saying that "The Winds Of Winter" will be released in 2016.
Here is a conversation between a radio host and Cuervo:
Radio Host: The sixth book will be?
Cuervo: It is expected next year.
Radio Host: In English, but in Spanish when will it be?
Cuervo: We have been promised the manuscript in advance of the release in English which we will translate; there won't be a big difference.
Radio Host: But you are equally sure it will be next year?
Cuervo: Well, let's see, confidant [sic]...but a meteor could fall.
The conversation is a true indication that Martin has already completed the book ready for publication next year. Since Cuervo is well known to Martin, fans can trust his information when it comes to the release date of the long awaited book.
It is possible that Cuervo is teasing on a catastrophic steroid coincidence with earth, stimulating an extinction-level-event and robbing other publishers of book six in the series. It is possible that Cuervo is referring to the red comet last speculated in "A Clash Of Kings" returning for a different, closer, more deadly pass.
Regardless of the implication of Cuervo, the book is in pipeline. In the meantime, fans can focus on the consistently on-schedule HBO version of the series, the Captain Cosmos that might be coming out.