I know that if I add a forum only a small percentage would click through to it. So what volume of traffic would allow a forum to start - even a slow start?
I've been exploring other forums in this niche and none have large audiences, however, even the small ones add a sense of community for those that use them, and that's something that visitors in this niche could use (people with a problem).
My primary goal is helping my visitors. The more long-tail search terms I read on GA, the more I focus on this goal. I think a functioning forum would be a good thing for these people.