I think GRRM made his story too big, forcing him to juggle with too many characters and storylines whilst also havng to deal with the aftermath of a time skip not taken. For example. I think (quick google not sure if correct) Arya is 9 years old at start of the novel, she is currently 11 years old as of ADWD. Now it seems to me Arya was to be trained as a faceless men and become a deadly assassin. No matter how clever you are, you can't be taking seriously, as the deadliest of assassins at age 11. All in all i think it has left him with some form or burnout. Like he can't get the motivation to knuckle down. or more accurately, he is having a hard time finding the forest amidst the trees, and is not making much progress even when knuckling down leaving him demotivated in the long run.
Meanwhile he is loving working on all the other stuff. Maybe cause there , he still got a clear overview. He sees the start, the ending and everything in between. Those projects may be a breath of fresh air from the fog that has become the main story.
Obviously all of this is my conjecture/speculation. I don't know GRRM. I might be entirely wrong.
In any case i've enjoyed the works he has put out. his books are amongst the best i read. Him not ending the story won't change that.
Obviously i would like to know the ending of a story. I guess that's human nature. I mean some people are fine with open endings to stories, but usually i prefer a form of closure from the stories i read. All in all, if GRRM doesn't finish, than that is what happens. I'm okay with it.
If he doesn't want other people to continue writing the story, then i'm naive enough to hope people won't do so. In truth i never enjoyed series in which other writers took over as much from that point onwards. You can tell the mind behind the story is not the same as the mind that wrote what came before. Though i'm holding out hope for some sort of quick synopsis on the ending from GRRM himself, if he ends up deciding not to finish the story (or life decides for him or myself - Hope i haven't just jinxed myself, as i hope to continue living for quite some time).
In some way you can argue we already have a rough view of the ending GRRM envisions thanks to the tv show. But the tv show went bad real fast once past the book materials, and it was clear the show writers couldn't resist twisting the story to their liking/viewpoints on life/modern society during the final couple of seasons.
