GOT now has two real world threads (at least)"
The written universe which has lasted for five novels and was supposed to go for at least two more. In the meantime there have been additional works published by George R.R. Martin and and with others. So I hesitate to affirm that 'x' books are out there. There are a plethora. And that makes sense because George R.R. spawned a massive world of continents and kingdoms, with many primary characters and locations. Also multiple religions and contrasting belief systems.

The televised universe was handled by some very good producers who started their series with some incredible visuals and accompanying music. As time went on their world caught up with the written world, and eventually went past it. And ended with many of the main characters biting the dust with the knowledge of but maybe not the complete endorsement of George R.R.

I believe that George R.R. is still active enough to continue the first universe, we shall see.

Best.Dragons.Ever.