On the BA Board, we do split out the threads that get too long into annual threads, closing the older threads. An example of this would be the catering threads such as this one -
https://www.flyertalk.com/forum/brit...025-first.html as the menus change regularly.
The one you have linked meanders back and forth with not much change in the information, hence we have not split that particular thread out. Feel free to ask your question in it and the wealth of experience will soon have it answered quickly enough.
However, BA the moderators will consider it for the annual refresh at the end of the year.
As for general FlyerTalk archiving, I will leave someone better qualified than me to answer.
aks120
Moderator: BAEC Forum