Use your imagination for just a moment.
The torrent is an example of the system I am describing, not the same system. Torrents cannot work for live streams because the entire content is not hashable yet, so already you have to rethink how it's done. I am talking about adding a p2p layer on top of the existing streaming protocol.
The current streaming model would prioritize broadcasting to high-bandwidth users first. There should be millions of those in a world-scale stream.
Even a fraction of these millions would be enough to reduce Netflix's streaming costs by an order of magnitude. But maybe Netflix isn't interested in saving billions?
With more viewers, the availability of content increases, which reduces load on the centralized servers. This is the property of the system I am talking about, so think backwards from that.
With a livestream, you want the youngest block to take priority. You would use the DHT to manage clients and to manage stale blocks for users catching up.
The youngest block would be broadcast on the p2p network and anyone who is "live" would be prioritizing access to that block.
Torrent clients as they are now handle this case, in reverse; they can prioritize blocks closer the current timestamp to created an uninterrupted stream.
The system I am talking about would likely function at any scale, which is an improvement from Netflix's system, which we know will fail -- because it did.