I have a sneaking suspicion that there is a big overlap of the early adopter core user bases from kuro4hin, slashdot, reddit, and HN - i.e. a lot of the same people moved from one to the other and created the editorial direction (so to speak). By that measure HN is 'the next Reddit'.
Unless HN starts supporting sub“HN”s (or starts allowing porn, jokes and My Little Pony-related posts on the frontpage) I don't think it's a viable replacement for Reddit.
It's already got a lot more political stories (though necessarily post-Snowden); HN feels pretty much like early reddit now. Though I do think Reddit morphed its community precisely to avoid just being another in this list (Digg exodus helped that too of course).
