The sad thing is, no one has noticed that Hangouts is invoking a WebRTC plugin in my PulseAudio container, leading me to believe that they're already experimenting with WebRTC.

With WebRTC, a proper signaling protocol (they're probably using Jingle anyway, give the RTC history and the fact that RTC relies and builds on Jingle), and a relay server, there's not much to need to do to interoperate if they wanted to enable it.

This whole notion that they "can't" make it interoperable or that it will "slow them down", is complete and utter shit. Slow them down on what? All I've seen so far is more merging of GoogleTalk+GooglePlus and a rebranding effort. Basically no new feature, no integration with Google Voice, no seamless integration with SMS.