Essentially it's a good idea, but I would have some concerns:
firstly, I think it would be widely open to abuce. people who might want to start a fight might choose this topic to start it, knowing that it would all kick off but that the thread would be deleted after 10 days so essentially it wouldn't matter.
People who might want to make really nasty comments on a thread might wait until the 9th day to do so, and then go forth and post, knowing that their comments would be deleted anyway thus giving them licence to say whatever they want.
someone might start a thread in this section and it might end up in useful discussion which might benefit people in the long-term, and after 10 days that discussion would be lost.
re news threads, while I can understand peoples' feelings on threads that are currently active in the news, I don't think such threads should be deleted after 10 days, firstly because this news story is still ongoing, and rightly or wrongly, people wish to discuss it, so to delete it after 10 days would take away the continuity of discussion, and secondly, if, as has been pointed out, a parent that was at the centre of such a news story were to come on in the future and discover there were no discussions relating to what they had been through, this might cause more upset than what had actually been discussed, esp given that most is positive, and the majority of bickering had gone on between users, not against the parents iyswim.