HTTP, SMTP, and XMPP are already functionally decentralized. We still need decentralized protocols for web search, tweeting, social networking, VoIP, and a bunch of other things.

In a world where every person runs their own cloud server, all we really need to do is install the same apps as each other. Apps can just invent their own (open) protocols and other developers can make apps that interoperate. Standards can emerge naturally over time.