Ask HN: How to stave off decline of HN?

I was just asking RiderofGiraffes if he had any suggestions for fixing the decreasing quality of comment threads on HN (http://news.ycombinator.com/item?id=2403449) and it occurred to me that I might as well ask everyone.

Anyone have any suggestions? We're on mostly uncharted territory here.

The problem has several components: comments that are (a) mean and/or (b) dumb that (c) get massively upvoted.

I don't think you really can. This site is a community and the users matter above all the features. If the user quality takes a nose dive all you can do is hold off the inevitable with new comment rankings. Every site has a point where it gets so big it declines in quality, reddit hit that and now those who want the old reddit back are coming here.

The only way to truly guarantee it would remain high quality would require credentials to use the site, or require invite/referrals, but then that has a whole host of its own problems.

I'm relatively new so I don't know what HN "used" to be like, but in the short time I've been here I've noticed it decline. It seems to me that more and more people who aren't knowledgable or have insights to offer are joining and people like jacquesm and riderofgiraffes are leaving. It was inevitable and has happened in every community I've ever used.

I could see that being the case with a trend/fashion, but it's not so much of a problem with other things.

A hard ban on politics and current events, instead of the wiggly one we have in the site guidelines now.

This is a separate issue, but one thing that is not perfectly clear to me is what an upvote/downvote is supposed to mean. Does it mean that I agree with the comment, or that it adds to the discussion?