Auto-closing is not an issue and could be implemented in community-friendly fashion. Just make a bot post "this ticket is dated, leave a comment if it's still i

Auto-closing is not an issue and could be implemented in community-friendly fashion. Just make a bot post "this ticket is dated, leave a comment if it's still important and revelant" then wait a few days and close only ones that don't get much attention. Simple and user-friendly.