But it will be up to the executors of his estate to pursue legal action.
Regardless, it wouldn't be based on the series. The show diverged before passing the books.
I believe he was under a contractual obligation to deliver on the sixth book before season six. Not sure how he got out of that. The benefits of bilateral monopolistic negotiation, I suppose.
Does anyone know if there are any betting markets for when/if he will finish book six?