A bit about the big boards/biggest forums/largest forums
Mojo you're talking deep, sweet and it's a pleasure to read and reread your post.

The only thing I wish to explain is that it's not exactly true that
forums are on the decline
and there are some noticeable (noteworthy) examples (if we own something like this, we'll be probably very rich

):
Some of the biggest/largest forums
Some of these
biggest forums (
largest forums) are (links to their Alexa.com's rankings):
http://www.alexa.com/siteinfo/conceptart.org (with currently 3,599,276 posts.)
http://www.alexa.com/siteinfo/gaiaonline.com (with currently 2,319,787,683 posts)
http://www.alexa.com/siteinfo/d2jsp.org and so on, and so on.

So, well, according to their ranks and their amount of content (posts/articles) they're pretty popular.
My idea is, there is still a lot of opportunity for the forums, but not for
every forum.