Agreed. I think HBO would be better off waiting 15 years. Give it a total reboot.

Hopefully Martin will have finished the books, but in the pretty likely event he never does, you can still swear up and down you have a full outline this time. Throw in an opening flashforward to something like King's Landing taken over by the White Walkers, as a promise that winter's going to be real this time. While you're at it, let Bran die instead of just getting incapacitated. His only purpose is to become king, anyway, and killing him would leave the endgame in question.

As long as the story is heading in a different direction, I think there's enough versatillity to the source material that a strong filmmaker could create an entirely fresh take on it. But you'd need to wait until our culture's nostalgia becomes more powerful than our disappointment. Prolonging the current era with unwanted spin-offs will just dilute the brand for a longer time, like how J.K. Rowling's repeated returns to the Wizarding World have kept everyone burned on Harry Potter.