I've been working on a network of small communities and I'd tend to agree that these are the path forward. Even so, all 3 points you make are valid. I have no idea how I'd ever monetize the thing, and the only way I've been able to find interesting people is via direct recruiting (on average, the organic users have less to say).
I've been trying to open the network up to the public more, but I'm starting to realize that making the communities more insular and invite-only had been more successful - but that's very hard to scale.
The site is https://podaero.com - always appreciate new users.