So what you're saying is that you think George R R Martin should not see a dime of revenue from the hit TV series made off of his books? Because Game of Thrones came out 20 years after the first book was published.
Maybe it would have encouraged him to write the last books and thus have an ending
First of all, your timeline is off: A Game of Thrones was published in 1996, and the Game of Thrones series premiered in 2011.
Second of all, even if you were correct, that would only apply to the first book, not the subsequent ones, which were spread out across 1999-2011 (indeed, A Dance with Dragons came out the same year as the TV series premiered).
So perhaps you'd like to pick a different copyright maximalist strawman?
Mr. Martin was also paid to support the production of GoT, not just royalties. There is no reason to believe that he wouldn't be called to do the same sort of consulting work on the script, dialogues, visual, etc if the copyright expired.