Idea - The ability to set a delayed lock of a post, with a notification to people in the thread or currently typing that it will lock in # number of minutes/hours.
Another issue, that people who are posting or have posted before a thread gets locked, that they will completely lose whatever they typed when that happens. There should be a 'sandbox' or a window in a thread that keeps content despite the thread being locked for a certain amount of time to enable people to repost it in another thread.