I think POSCON will draw in pilots with some of the key features that separate it from the other networks. VATSIM will have a difficult time drawing in people when it loses to things like a faster server update rate, a good controller client that can emulate real world systems better, not being kicked from the network for grabbing a bite to eat, etc.
Even if POSCON only meets half of the features they list on the front page, its a promising start and I think people will realize the potential. Yeah, right now it's a lot of talk, but everything that's been done so far is paving the way for a network to cater to both pilots and controllers. I like to think of POSCON like Amazon, and how Amazon disrupted retail. POSCON will disrupt the online flight sim community, its not a matter of if, but when.