A more interesting question would be: why shouldn't HN revert to the mean?

EDIT #1: The speed at which I'm being down-voted warrants some further explanation...

The article headline raises a question about the potential decline of HN as a "quality community". The fact of the matter is that with all things being equal, HN is just as susceptible to decline just as much as Digg or reddit - HN follows the same "social news" principle after all.

So then why shouldn't it follow the same principle?

In attempting to answer this question I'm hoping that members will forward ideas to counter this principle in general, given that all things are equal in this space.

EDIT #2 [on a separate note]: I should add that the future of HN (or Digg or reddit) ultimately depends on the demand of the community. If we get an influx of users that want to discuss:

Ruby vs. Python

Emacs vs. Vim

Bootstrapping vs. Funding

Or whatever else comes to mind, then so be it. Btw, we've been good as a community in avoiding religious discussions, so I'm pretty happy to be insulated from the whole Mac OSX vs. Vista debate!

The bottom line is that we can draw parallels to other communities that have risen/fallen based on the whim of the dominant memes that come and go, but eventually the fate of this place relies upon what memes we choose to propagate.