Note: Posting broke for me. Not sure if this is a dupe.
It would nice to have an option to auto close topics after xx days if there hasn't been activity. A process (maybe manually started) that sweeps open topics where the last post is xx days old. I'd set this at 60 or 90, but I could see other values. This would close those threads.
Users could request reopening or start a new topic, linking to the old one. Either works for me.
This helps in a couple places
1. a user hijacks a topic to get their similar, but different question answered
2. spammers post in a thread because of a keyword they like
3. Helps keep traffic growing