Perhaps there should be a time limit on the related posts that appear in the right-hand column, say a year since the most recent reply.
On the Boston board, e.g., there was a new post about a Burmese Food Festival next week in Lowell. One of the related messages was from a food fair in 2008! The most recent reply was in 2011. Useless, particularly for an event. Even for a restaurant still in business, stale information can be misleading.
I'm still advocating some kind of a "Colour code" idea for all threads.
Once any thread is 6 months old,
the title isn't bold anymore, or
it has a light gray background [but much lighter than the "you've read all of this" or
black is newer and blue is older
Clearly, there are tons of options....