Did you read the article? It's about weakening, not replacing.
As I say:
«Facebook is taking over the web and we need to save it. The issue is too complex to have one solution. The most obvious solution is federated social networks, but it’s also a very long term solution. We need more, sooner. One of these thousand small solutions should be to take back chat and subscriptions, by making them dead simple to use for everyone straight from the browser.»
While commonly used, chat is just one feature there. There are many popular and closed chat services like Whatsapp for example which aren't connected to social networks. So I don't see why you focus on this problem in the context of Facebook. The problem is a problem in itself. I.e. "how to break the walls of walled garden instant messaging networks".
As I say:
«Facebook is taking over the web and we need to save it. The issue is too complex to have one solution. The most obvious solution is federated social networks, but it’s also a very long term solution. We need more, sooner. One of these thousand small solutions should be to take back chat and subscriptions, by making them dead simple to use for everyone straight from the browser.»