Originally Posted by George RR Martin
The season that's about to debut covers the second half of the third book. The third book [A Storm of Swords] was so long that it had to be split into two. But there are two more books beyond that, A Feast for Crows and A Dance with Dragons. A Dance with Dragons is itself a book that's as big as A Storm of Swords. So there's potentially three more seasons there, between Feast and Dance, if they split into two the way they did [with Storms]. Now, Feast and Dance take place simultaneously. So you can't do Feast and then Dance the way I did. You can combine them and do it chronologically. And it's my hope that they'll do it that way and then, long before they catch up with me, I'll have published The Winds of Winter, which'll give me another couple years. It might be tight on the last book, A Dream of Spring, as they juggernaut forward.