Really, asking "what should replace Facebook" is putting things the wrong way around.
A more interesting way to ask the question is, "what did Facebook replace."
People used to build their own websites. People used to have blogs. People used USENET which was truly distributed and un-censorable.
Facebook and Google took the open internet and open standards and monetized and made everything crappy. Enough of that. Nothing should replace Facebook, it's done, stick a fork in it.
@hhardy01 Let's not be reductive.
Facebook works, regardless of whether you have tech abilities or disposable income.
Facebook centralises and logs communication in a way that IRC never did.
Facebook is accessible and convenient af. Any competitor has to match that.
IRC has always used a server. And there's been bots such as eggdrop since forever. Try freenode and irissi client now.
@hhardy01 I'm sure it's doable in some form. The problem is, it's not accessible enough for someone to go from ignorant of the technology to fully integrated, without substantive research. If I say 'join Facebook' to people, they can can find Facebook, and from there the onboarding process takes them through to completion. (Even then, the grossly tech illiterate can struggle.)
That's the barrier we need to surpass.