Someone desperately needs to come up with an open source replacement for GitHub that is completely decentralized. Sure GitLab exists and the repo is decentralized since it's Git, but issues, merge requests, comments, etc aren't Git based (though they could be)
Phabricator is awesome but GitLab is more similar to Github if you're looking for a direct replacement.
These are still centralized, but each organization can host its own server. A true decentralized solution would federate issues/tasks, pull requests/diffs and their comments, etc. similar to how Git federates changes.