Strangely you would say: if something works as a comic, it would work as a movie too, because both are so visual. But not sure if that's entirely true, because even comics and movies are quite different mediums. Also the scripts for the comics were written especially for the comics. SK never writes a book with a movie in his mind - his books are way too broad and sprawling and feature way too many characters to be ever filmed literally.
But funnily George Martin designed Game of Thrones in a way so he thought it could never be filmed. He was tired of his stories always be filmed the wrong way, so he wanted to write something no one would ever be able to adapt. And it became one of the most successful shows of all time!
It all comes down to finding the right interpreter of the material.
I personally think you can film any written material. Not literally often, but you can always find a way to adapt it in a filmic sense without losing the 'soul' of the original material. In King's case it comes down to the characters: all the successful adaptations had good actors attached. I you can get the essence of his characters on screen you already go a long way.
But funnily George Martin designed Game of Thrones in a way so he thought it could never be filmed. He was tired of his stories always be filmed the wrong way, so he wanted to write something no one would ever be able to adapt. And it became one of the most successful shows of all time!
It all comes down to finding the right interpreter of the material.
I personally think you can film any written material. Not literally often, but you can always find a way to adapt it in a filmic sense without losing the 'soul' of the original material. In King's case it comes down to the characters: all the successful adaptations had good actors attached. I you can get the essence of his characters on screen you already go a long way.