Within the next 10 years, and maybe much sooner, the vast majority of content on FB/Twitter/Reddit/LinkedIn will be completely fake. The "people" on those networks will be fake as well. Sure there are bots today, but they're not nearly as good as what I'm talking about, and they don't exist at the same scale. Once that happens, the value of those networks will rapidly deteriorate as people will seek out more authentic experiences with real people.
IMO, there's a multibillion dollar company waiting to be founded to provide authenticity verification services for humans online.
Any kind of widely used identity/authentication system would need to be a protocol and not a product of a for-profit corporation. Businesses take on great risks if they use another corporation's products as part of their core operations as that product owner can change the terms of service at any time and pull the rug out from under them. A protocol is necessarily neutral so everyone can use it without risk in the same way they use HTTP.
For identity protocols I think BrightID (https://www.brightid.org/) is becoming more established and works pretty well.