There’s an article on Wikia/Fandom from last year called “Is It Time to Give up on George R.R. Martin’s ‘Winds of Winter’?” There’s talk in there about his health and how long it’s been since he started on it. What it doesn’t address is will it even be worth it.
As the TV show goes on and Martin is more and more involved with the announced spin-offs, it’s going to reach a point where those last two books will become less and less important. Once season 8 is done in 2019, fans of the TV show will think, “The series is over, so I’ve seen the entire story. Why should I bother waiting for books that might never come?”
The ones that have been reading the books might stick around because they want to see the details that can’t be easily translated into television, but he’s been working on “Winds of Winter” for seven years now with no release date in sight. Will “A Dream of Spring” take another decade to write after that? Wanting to write books “that will stand up to the test of time” is a nice idea, but he will be 70 in September. Does he have another decade in him?
In June 2016, Martin had a chat with Stephen King at the Kiva Auditorium in Albuquerque, NM and asked King how he writes so fast. King spends 3-4 hours a day to get six “fairly clean” pages, so a 360-page book will take him about two months if it goes well. Martin’s admitted he gets writer’s block, re-reads/re-writes what he did the day before, is distracted easily and he can only write when he’s in his own home, so the frequent trips he’s been taking relating to the show and the books means no writing on the novel gets done.
All of that is leading up to that it is very likely he won’t finish book #7 before he dies, and many people will consider the TV show a more definitive version than a book that might come “someday”.

