“There is certainly no lack of material,” Martin told Entertainment Weekly when pressed on the topic last year. “Every episode of The Naked City -- one of the television shows I watched as a kid -- ended with a voice-over: 'There are eight million stories in the naked city. This has been one of them.' There are eight million stories in Westeros as well . . . and even more in Essos and the lands beyond. A whole world full of stories, waiting to be told . . . if indeed HBO is interested.”
Hey, George -- they're interested.
In all the speculation, fans and Martin alike turn to one source material for a potential follow-up: the author's "Dunk & Egg" stories, a series of novellas set 90 years before the adventures of Jon Snow, Tyrion, Daenerys. Dunk is Ser Duncan the Tall, a nomadic knight who gros up to be a member of the Kingsguard; his squire Egg grows up to be Aegon V Targaryen, father of the Mad King, whose legacy currently plagues the lives of our current heroes and villains. A series following the two could go literally anywhere -- which makes it an easy target for adaptation.