I think he's in a pretty bad spot with regard to the main GoT story. I think the biggest thing that made everyone turn on the show in the last season was Daenerys turning into a psycho so suddenly. Even though there is foreshadowing of it happening going all the way back to early in the series, she still goes from risking everything for the good of the people to mass slaughter in 2 episodes. They put in plenty of smaller atrocities along the way, but it was always framed as her just going a bit too far with good intentions. If they had shown her more clearly being ruthless and movitvated by lust for power, she would have lost the loyalty of people who have brains and integrity like Tyrion and Varys. They tried the shoot it down the middle by making Tyrion get kind of dumb and giving Daeny token atrocities like burning the Tarleys and triggering events like the deaths of Missandei and Rhaegal but people just didn't buy it.
It's a real tricky thing to write. Maybe Martin could have pulled it off, but the TV writers did not. Now Martin is screwed because the story is already out there and people are mad and he's somehow supposed to pull off this already difficult trick for a bunch of people who are already mad at it. Seeing how he's already fabulously wealthy and money is still rolling in every day, given the choice of living the rich guy lifestyle and relaxing for the rest of his life vs. writing something really difficult that is just as likely to further tarnish his legacy as redeem it, it's not that surprising that he just decided to punt.
