And yet... here we are. I've always assumed book 6 is about the Tyrells taking over King's Landing and fighting against the Martells by proxy through "Aegon Targaryen", and Bran (and possibly Jon) continuing to explore beyond the Wall. I don't even know where the hell the rest of Greyjoy's fit in, or Sansa and Littlefinger, or even Tyrion. But yeah, too many threads for Martin to tie up in two books.