As long as there is an identity that people find distinctive at HN, I don't think it will die.
All of the suggestions here kind of fit into that paradigm for me....how do you control/preserve identity?
- You could give old timers more control (downvoting)
- You could give newcomers less control until they prove themselves (no account creation just to upvote your friend's post)
- Enlist help in keeping tracking/managing the pulse of the community (like reddit, which has multiple admins on the lookout for issues)