Both authors have said they have a 9 or 12 book (12 is the most recent info they've given) story all boarded out and mapped/planned. So, another 3 or 5 books, at least. They've also said that due to ratings and how much the execs love the TV production, they plan on a long Game of Thrones like run. The TV series is just picking up steam too IMO, this season has been fantastic so far, the 2 episode opener, and it's apparently according to those who have seen the first 1/2 or so of the season's shows that are "in the can", it just gets better. Can't wait, this is the best TV out there right now.