I've seen many forums change their entire nature over their lifespan due to many factors (owner deciding a racing game and car culture forum should be strictly about actual racing resulting in a forum valued at almost a million dollars becoming deserted within a few months, a hack resulting in the total loss of what came before and destroying any motivation by the members to rebuild it, new owner's decisions resulting in pop up ads/giant banner ads/video ads on every...single...page, gradual loss of interest/people moved on--usually when a forum has too narrow a focus), but Talkbass is one of the few that remains mostly unchanged since before I signed up.
Every forum has the old crew who signed up in the beginning or shortly after, who get whittled away by changing interests/life/getting banned. Eventually they're gone and what you have left are regular users who use the forum as intended and the people who remember the old crew, who go on about how great things used to be back in the day while ignoring how the forum generally becomes more refined and better organized over time, with generally more professional moderation (as opposed to "I would ban you, but since we're buddies and you're the 14th person to register I'll crack a joke and ignore it").
Talkbass is fine, from what I've seen. Popularity of the forum will ebb and flow, users will come and go, but hey, at least it's not reddit.