Of course it's still alive 😊. New features are consistently added and bugs and quickly squashed. We've huge plans to grow CB even further with CB 3.x as we try to reach beyond Joomla (into WordPress and eventually Standalone).
This showcase forum is entirely a community showcase. Whether someone shares their site or not is up to them and whether it remains maintained is up to them. Our demo site below can always be used as a reliable way to check out features and is always maintained.
demo.cbdemosites.com/
If you've any questions feel free to ask!
As for success stories we've several users running large successful businesses, but I imagine they want to remain private. Maybe they'll contact you privately, but that's not for us to decide. CB is also extremely popular for internal intranets for companies (employee to employee platforms).