George R. R. Martin is open to aGame of Thronesspin-off.
When that time comes, Martin says he believes there are many opportunities for another show.
There is certainly no lack of material, Martin told EW.

Credit: Nick Briggs/HBO
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.
But which one of those millions of stories would make the best filmed project?
A prequel set during Roberts Rebellion, perhaps?
Or a sequel set after the events in the current show?
All this remains conjecture at this point, however.
Preview:
For more of Martins thoughts,follow his blog.Game of Thronesreturns to HBO on April 24.