A few of us think it would be helpful to extend the _Chat and OTBT automatic pfffft facility to other/all topics.
My suggestion is that there could be a line under "auto complete links?" etc which would say "Set thread to expire" with a dropdown defaulting to "never" but with the alternatives "after thirty days" and "after ninety days". Most users would ignore it but it would be very popular with those who are posting something sensitive that they don't want to be archived forever.
I believe that this would reduce non-Chat traffic in Chat (frequently complained about) and encourage people to choose the right Topic in the first place, attracting the right traffic.
I know Tech are hopelessly overworked with very urgent projects like app updates etc, but the reason I'm suggesting this is that the background code obviously already exists for threads to disappear automatically after n days so it's not lots of complicated work.