This one admittedly could be a tough one to do within budget, unless it's animated. but there are over 20 books you can have a Simpsons level of seasons without issue. For those who don't know this series it is a re telling of post world war 2 history after a virus from space turns many of us into hideous freaks (jokers) or superhumans (aces) a more realistic portrayal of the superhero genre where many with powers don't just don tights and fight crime. It was also a shared world anthology Martin started with a bunch of sci fi writers based on George RR Martin being the authors' GM in a Superworld rpg campaign. Securing rights could be a hurdle but otherwise damn this would make for some incredible tv easily as awesome as Game of Thrones.
The Hedge Knight/ The Sworn Sword
This one is both likely as hell and a huge no brainer. The Hedge Knight, and it's sequel The Sworn Sword. are prequels to Game of Thrones. And to be 100% honest Martin knows how to do an incredible prequel. Set generations before thrones, The Hedge Knight tells the saga of Ser Duncan the Tall, and his squire Egg. It is awesome to see house Targaryan in full swing, and Houses Stark and Lannister take a back seat in the story. In the books it was revealed that Duncan eventually becomes lord commander of the king's guard, and Egg is the only character who is in Game of Thrones (albeit is a very old man). That's what I liked most about this no overt push to link the worlds such as finding out dunk tought Tyrion to read, or inspried Robert's rebellion ala the Star Wars prequels which seemed to force as much reference to classic Star Wars as possible, especially if you look at the cut scenes. Star trek was equally guilty of this in the first season of Enterprise. These prequels are not nearly as political as thrones as they focus on a single knight's journey making an interesting change of pace from the main books. With the Game of Thrones series doing as well as it does casting a bunch of unknowns and using most of the same sets this is an easy sell to an established audience. We can only hope.