I read in Redmine - Evaluate Discourse that solved topics will be automatically closed after 30 days.
Can / Should we auto-close unsolved topics too?
IMHO it’s unlikely that someone will provide a solution after 30 days or even later. Someone just revived Why do page numbers keep disappearing? with some unrelated comment.
Maybe ask QA about their policy for Bugzilla and adapt it?
This was rolled back following this discussion.
Yup it’s technically possible (and is done on a per-category basis, so different languages don’t have to have the same policy). As for “should”, it’s up to you and other regulars 
Hmm. So how about giving some disincentive when posting under long unchanged topics? Like showing a warning box in the spirit of: “This topic didn’t have any new entries for a long time. [New topic] [New linked topic] [Reply anyway] [cancel]”, instead of the default “[Reply] [cancel]” after n days.
Maybe I’m just over-engineering for a non-existing problem… and I’m hardly a regular, so this would need more input from real regulars 