Ask HN: How to convert a WebRTC stream to RTMP?

We are developing a streaming web application that needs to broadcast a WebRTC stream to ~5K people.

But we have found that WebRTC has a theoretical limitation of 1000 users per stream. So, alone it will not work for our purpose.

We can either: A) Implement a solution that can increase WebRTC's number of viewers limitation. Do you know any solution for this? B) Use a transcoder to transcode WebRTC to RTMP, and then use a service such as UStream to broadcast to the audience. Do you know any WebRTC to RTMP transcoder service?

Thanks