Humans have a tendency to take the mental shortcut that scarcity implies value, and so I wouldn't be surprised if this were to actually increase interest in HN.

Humans have a tendency to take the mental shortcut that scarcity implies value, and so I wouldn't be surprised if this were to actually increase interest in HN. HN might also be one of the few sites able to conduct such an experiment (most other sites being worried about traffic, revenues, driving users away, etc.)