Doesn't seem to be a very thoroughly thought-out move to me. It is inevitable if current users are willing to compromise. And given the amount of gray-area, I think they are.

Quality doesn't just vanish. It's eroded away like the hair cells in your ear. When you realize it's gone it's not going to come back without clever engineering.

So it's not just as simple as changing the name of a forum, declaring a shift in the theme, that would move the forum in one direction or another. Unless you have superusers and/or admins. The analogy is to slashdot, or to reddit. Keeping the reddit-style system means increasing popularity leads, without a doubt, scattered focus. Keeping the focus implies a shift in the current moderation system (unless there are invisible superusers lurking around).

The flaw of forums is not in the rules, not the theme, not the users, but in the system design. Change it, or compromise. Either way, whatever is written so confidently on hackernews.html will not be as simple as "I decide it so."

The exception to my argument is if growth of userbase isn't a goal. I'm not sure if that's the case here though.

My biggest worry is a slippery slope. For instance, lately I've been reading lots about economics. A lot of it is stuff I would consider hacker-worthy. However, it might not interest some people, and others might have philosophical objections. Or even political objections. We're already, at that point, on our way downhill.