By the time a story needs to be vouched for, it loses the momentum it previously had gettting it to the front page. So you need a way to prevent vouching from being necessary in the first place.
If a story transitions to a high flag/vouch level (IDK, >10 of each), it should have its clock reset to be considered a new submission, regardless of dupe status. Maybe label with [controversial] or [hot].
This problem happens again and again with hot topics, and at the moment the default behavior is to let them disappear, which is a bit lame.
