Earlier quoted context omitted.
The next generation of social networks is already here. It's decentralized and open-source. Mastodon, Pleroma, PeerTube, loads more, all part of the same network, the fediverse.
I'm not sure it's really possible to launch new decentralized protocols anymore, and get any kind of mainstream traction. We have HTTP and email basically by historical accident. Even RSS was shown to really just be an implementation detail of Google Reader, and there wasn't enough of an organic ecosystem outside of that for it to survive.
I would assume that once a major media company or government organization realizes they can adopt an implementation of the existing protocol this will move that network a bit closer to the tipping point.