The series is not even finished. If the books end like the show it will be a dead franchise within a decade of the final book. The only way to truly save the ASOIAF franchise in terms of relevance is a full scale reboot of the entire universe like Marvel or DC Comics do every couple of decades. Reboot the entire series starting with maybe Robert's Rebellion or a generation before that. And license the series to literally anyone who wants to write in it like Marvel or Star Wars or some major franchise where there are so many characters and stories that no one can keep track.
ASOIAF is becoming more and more like Star Wars at this point and it is not even done with its first story. It is just mass marketed garbage that too many big companies have their hands in so it gets endlessly promoted due to corporate influence more than actual word of mouth. Star Wars has not been good since the 80s. But it has been a cultural powerhouse since then because the brand is everywhere. Roller coasters, video games, toys, comics, books, movies, shows, posters, commercials, and so on. How many people really care about Star Wars? Yet how many people know about Star Wars?
This is how ASOIAF is. Everyone knows about Game of Thrones. But no one cares. No one cares. So GRRM is doing like George Lucas did. And letting every company have his license for ASOIAF to churn out whatever they want. Card games, toys, posters, video games, comics, prequels, art books. Sure GRRM has not put out another book in the main series in a decade. But dozens of other ASOIAF projects have come out in that time to keep the brand active.
ASOIAF is like Coca Cola or Pepsi. Everyone knows Coca Cola and Pepsi. Yet they spend more on advertising than almost any companies in the world. Why? Because they are building brand loyalty and getting you to invest in the name to the point where you see 'Pepsi' and you instinctively buy. They put Pepsi products near the checkout to get those impulse buys and place the logos at eye level for maximum exposure. Just like when House of the Dragon premiers it will be mass promoted more than anything HBO has ever done. Log into HBO Max guess what show will be promoted? Do you need cancer causing bubbly liquid? No. But the brand is a huge part of your life because it has been mass advertised to you. Do you need more garbage fantasy novels and stories from GRRM? No. But the mass advertising will convince you that you do.
You need to watch House of the Dragon because everyone is. Do you want to miss out on the cultural phenomenon that is Game of Thrones Part Two? Do you want to see the greatest fantasy adventure of all time? Do you want to fuck hot chicks and have eight pack abs like the models in the Coca Cola advertisements do?