It would probably be possible for smaller communities today, given how cheap bandwidth already is. For comparison, I'm currently paying ~$13/mo for a (symmetric

It would probably be possible for smaller communities today, given how cheap bandwidth already is. For comparison, I'm currently paying ~$13/mo for a (symmetric) gigabit connection. The main reasons for transcoding are downstream bandwidth usage and codec support. WebRTC mandates VP8, so codecs shouldn't be an issue. Downstream bandwidth usage probably wouldn't be a major concern when it's viable to stream at 1080p to thousands of viewers from a home connection (though I doubt that's going to happen soon). So you could probably ignore transcoding entirely. However, marketing would probably be an issue, since this architecture would prevent streamers from having more than about a hundred watchers, meaning that the big fish would stick to Twitch. That said, I suppose you could have a failover system, where larger streamers would switch to a relay-based system.