Everyone saw this coming. Everyone. Even GRRM had to know by at least 2 years ago that even if he managed to hit the deadline on this upcoming novel there was no way he could then turn around an entire next novel in less time than it took to get the next season to television. This has been a forgone conclusion since Season One Episode One aired.
I am sure his publisher is pissed. It would have been a perfect storm of marketing mania to have the new novel released weeks ahead of the next season of the show, and it would have sold millions of additional copies. Now it’s relegated to also-ran status whenever it does come out, and while it will still sell millions of copies (I’ll be buying it myself) the publisher knows the sales won’t be nearly as strong as they would have been prior to the show spoiling everything.
And that’s the real loss here. Now we have the show acting as spoiler for the books instead of the other way around. Every pivotal “oh shit!” moment in the books will show up in the show first. Want to know if Jon Snow is really dead? Show. Want to know who Jon’s parents are? Show. Want to know what’s really up with Bran? Show. White Walkers? Show. Tyrion? Jaime? Arya? Where’s Rickon? Show, show, show and show.
I suppose you could still read the books if you’re really dying to find out how to make Manderley Eel Stew or how Lord Whosit MakesNoDifference successfully defended some castle somewhere only to be betrayed by his own nephew for some reason nobody cares about. Even if GRRM concocts a completely different series of events and ending to his story from that of the TV show, it’s going to seem like a reach to make the books look different instead of the canon conclusion to a much-loved series.