Ending a chat, showing archive

I've noticed a couple other requests for this, but it doesn't seem like it's being developed yet. Is there a hack to end a chat after a certain time and only show the archives? Our site will be having chats during football/basketball games, but afterward, nobody will be responding to the chat, so it will be pointless to be live. Also, since we can't delete posts, it will probably just get spam anyway.

Anything being developed ASAP or does someone know a hack to get around this??