I say k5 is alive because of two things: the community, and the trolling.
"ROR IHBT" you say, but I am serious. Let me explain.
I've been posting comments and stories at k5 for years now. (Yes, I once traded under a different name. So did anyone else with a little spice.)
It has changed, sure. It has shrunk, sure. But in my mind, it is now at just about the right size.
It's hard to tell exactly what the scale is. But as far as I can tell, we've got about 200 regular "contributors", not counting dupes. Of course, I am sure there are many more lurkers, and of course there's the people that post on the front page stories occasionally. Either way, the community is small enough to be a community. I see a nick, and I know "this guy is nuts", or "this guy lives in NZ", or "this guy has a raging hard-on for Ron Paul", etc.
This is a good thing. A random one-line comment from someone you've never heard of is easy to take out of context, and who knows what the hell they're banging on about. But when it's from someone you know (if only from their k5 personality), you can put it in context, figure whether they are joking, trolling, well on, whatever.
This is where the smallish size of the k5 community is a strength. Think of k5 from four years ago, or, say, /. now. Sure, stories got commented on more, but I didn't know who half the people were. New names were always showing up and old ones were disappearing. These days, you know who it is you're talking to. Odds are, they're an asshole, but you know where you stand.
In any case, there is a critical size at which communities change, and we're more in the "friendly village" regime than the "cold city" regime.
I like it, it's like a little bit of home.
Ok, now I must be shitting you, right? No.
The absolute worst thing about online discussion, as a general rule, is that people treat other online personalities the way they would treat someone in real life. In particular, people are tolerant of idiosyncrasy and there is always a presumption of truth. If someone comes up to you in real life and tells you a story, for the most part it is true. And if it's someone with whom you have some sort of relationship (professional, personal, whatever), they can't just make things up, because you'll find out eventually and stop trusting them. And we unconsciously continue to act on this presumption even when we're online.
But online, no one knows you're a dog. This is good for the dog, but not for anyone else. The absolute critical fail point of any serious online discussion is what happens in every single /. or Fark thread: as soon as the discussion turns to any interesting issue, some failfuck shows up with "well you think that's a great idea but I know it's a bad idea because my uncle died of that". Now, of course, in real life, if someone says this, one would typically politely change the discussion. The problem is that this kind of trolling always works when people take each other as acting in good faith. And the shit about that guy's uncle is never true.
Here at k5, we have found the cure. No one takes anyone seriously, and no one ever takes anyone else in good faith.
But this is a strength. This is an immune system.
If someone comes with that "it killed my mommy" shtick, then it's water off a duck's back. All the responses are "ROR YUOR MOM'S A WHORE, OR AT LEAST WAS A WHORE ROFL".
And then the serious people can get on with the serious discussion. We are immune.
All in all, k5 is easily the most intelligent community that I've ever found on the internets. Horsecock and all.