GRRM should have hired a co-writer as soon as HBO picked up Game of Thrones for its second season.
At that point, there's no way he could have not known that the show would overtake him.
He let his fans down.
He's a hack writer who did a good job world-building but has no talent to finish it as a story.
I'm happy for him in the sense that he was a working writer who got rich...good for him as it goes...but we have to stop pretending he's a good writer if his behavior is to be understood.
But imho, he's more than just a hack who made good...he should have known better than to let his fans down like this...he should have hired some help.