Yeah, I don't think that it is boil the ocean difficult but there is definitely some complexity there.
I have been working on a scala WebRTC server, but I am not sure if it would really work at a large scale
Here was my basic approach:
An end user creates a PeerConnection with a Publisher node and starts sending a MediaStream using a string identifier.
Then another user can create a PeerConnection with a Subscriber node using the same identifier.
The Subscriber node then makes a request to the Publisher to make another PeerConnection to a Registry that exists on the same node as the Subscriber.
The replicated MediaStream can then be attached to the Subscriber.
Since the replicated MediaStream is in a Registry, any additional subscribers can attach the MediaStream on the same node as well.
The code is a huge mess but it is here (The scala server is in the media directory):
https://github.com/jgrowl/livehq
There is a vagrant file that brings up the whole system at the root of the project (using docker). I have not tested it recently on anything other than ubuntu.