It sort of depends how you define “replace GitHub”… GitHub serves at least two key purposes for most projects - a server for their got repo and a social layer to manage code changes. This project is only focused on the second purpose, which is where GitHub offers its most distinct features. There are many GitHub alternatives for git servers.

So this project is a stepping stone to completely replacing GitHub, but it can’t replace GitHub on it’s own an the data still needs to be stored on centralized servers somewhere (even if it’s a home server).