If I don't merge records on the duplicate record queries, will they remain there forever?

If no merging duplicate record action has been taken on a Person or Household record within 45 days of being flagged, the system will automatically unflag the record as a duplicate. Organizations will be unflagged after 90 days.

There is parameter gives schools the option to show all dupes or just the recent ones for those queries:
https://axiom.veracross.com/#/detail/system-parameter/270/380-general