Even with the discussion section, there are ideas or questions too short or inchoate to be worth a post.
This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.
I think most of these topics fit in. Intelligence explosion/FAI/SIAI are all existential risk related making them important applied rationality topics. Cryonics as well; the SA incompetence thread continues to attract discussion. Any ability to enhance human intelligence has important consequences for rationality. The only thing you mention not directly related to rationality is the singularity.
I view the discussion section primarily as a forum for rationalists rather than as a forum for the discussion of rationality (though that is obviously a natural topic for rationalists). I am curious how much people disagree. If the discussion section got too busy, we could add further subreddits.