In GC or EoEO, I'd say close the threads.
However, I could definitely understand leaving them open in the gaming forums. I've noticed several threads being closed in FF7 forum lately for that very reason. Now, if someone wants to discuss that topic, they see a closed thread, and have to make a new one, where a lot of the posts will probably be just stating the same things discussed in the closed thread. So why close it to begin with? What does it matter if a thread about chocobo breeding was made 3 months ago? Chocobo breeding doesn't change. A thread about chocobo breeding now will have identical discussion to one made a year ago.
So I'd say leave 'em open in the gaming forums.
