Does a comment need to be seen by many users to be worthwhile? If it contributes to the discussion of a small group of users (who may not have over 1000 karma), is that not still valuable discussion that you would want to continue? I understand the goals of trying to promote healthy discussion, but I fear that this will have many unintended consequences.

Comments are often used as communication between specific users and not necessarily intended for widespread consumption.

Can you give us some indication of what % of active users have over 1000 karma?

It seems like a fallacy that if a comment isn't read and endorsed by users with over 1000 karma within a certain timeframe it will never be influential. Weren't most of the literary and artistic geniuses completely unappreciated by their contemporaries? We may not be a literary and artistic community, but I think the rule applies all the same.

Nonsense. Lots of conversations continue with an interested subgroup, especially new or niche topics. Its easily possible no one with 1000 karma will ever visit.

Which means such topics are dead to HN. What remains? Something we can't predict right now, but I suspect it won't be what we want.

But that would be a reason to show it, not hide it.