Via Variety (and, actually, a recent interview or two), George R.R. Martin has revealed what section of the second series he’ll be writing. A bit of spoiler protection is in order…
”... the novelist, who writes one teleplay per season, will pen the Battle of the Blackwater, a huge army/navy slugfest that takes up several chapters in the second book, “A Clash of Kings” (and could be, um, expensive).”
On top of that, the article mentions that executive producers and lead writers David Benioff and D.B. Weiss have considered a season 3, and how to film it if it comes to it. It’s suggested that it’d have to be a long season… or maybe two seasons. Where to split it?
Sounds like it’d be the Red Wedding. A heartless cliffhanger indeed!