When it comes to learning, sharing, and growing together, online or otherwise, there are no competitors, winners, or losers. Just a bigger pie. (Good luck to lobste.rs, but I'll probably be staying right here on hn.)
I've been a contributor on HN for around 5 years and over the period of time I've seen a constant decline in the quality of comments, community support (read some of the 'Show HN' posts) and to an extent even the quality of the stories submitted.
A new improved hacker/startup community can be a serious contender for replacing HN (in its current state), just like Reddit is/was to Digg and others.