Sites that consist only of conversations are very hard to sustain. You need to build a community around a central activity shared by the community members. We don't go to places or join communities just to chat or post messages, whether online or in the real world. Dialog and conversation are always incidental to the main activity. This cafe we're sitting in is a community.
People come here to eat.
While they are here, they form communities and they engage in conversation. But if there were no food here, no purpose in coming here, those communities wouldn't exist. The notion that an online community can be solely about coming together to talk is going to be less and less successful. If the truth be told, it's an idea that's never worked very well. The most valuable use of real-time chat is around planned, structured events or offerings.