I think the moderators have been pretty clear in different venues that they are done with this when CentOS 7 end of lifes. Moving the forum to read-only and scraping/archiving the public discussions at that point is probably best. At that point put a placeholder to the scraped site and a link to future discussions to the
discussion.fedoraproject.org system. I think the types of discussions for CentOS Stream 9++ will mesh better with Fedora as they are both more 'update weekly to see what is coming' focused than the 'long term sit and update when I have to' production that older CentOS releases were known for.