Status of networkd as default?

We’ve currently got our scripted networking (default) and an implementation with systemd-networkd (enabled by networking.useNetworkd).

@fpletz held a talk at last years NixCon about making bringing networkd up to par and making it the default (Franz Pletz - Redesigning NixOS Networking (NixCon 2018) - YouTube).
@globin also stated that as a goal for the next release (19.09) here.

Now I’m wondering in what state it’s currently is and whether there is an overview of what’s missing to make networkd the default?

The assumption of course is that this is what we want to do - @edolstra has already opened up a GitHub issue tracking that migration.