The same art in different formats takes on different power. That is why movies are so much fun when one’s favorite novels are adapted. Think about the phenomenon of Game of Thrones. The novels are a different beast, but it is the show that has catapulted it into popular culture history. The story is there, though more superficial, but the visuals are worth the cost. We will even see how they can be separated but still be related.
The show has surpassed the books, but that does not matter.
The plot may have been laid bare in front of us, but the sensuality and images of the written word have yet to be presented. Many will buy The Winds of Winter the moment it is released, regardless of any frustration with the delay between books. The immersion of Martin’s words are worth more than the image of Drogon reigning fire on an army of Lannisters — though that is exciting for obvious reasons.
We have waited twenty years for the dragons to become powerful enough to make a difference, and with the television show we were able to see it presented in all its magnificence.
But imagine what Martin will do with that scene. Imagine how the battle will be told from whichever POV character he chooses — though money should be on Tyrion and Jamie.
Format is a tool. Each tool has its purpose. When used in conjunction, they can create something awe inspiring.