WebRTC gains a lot more than just being available on Chrome and on Android. These two open projects mean that WebRTC gets adopted in many non obvious places. Call it the unintended consequences of having Google bring WebRTC to life.
Set top boxes may be running WebKit, but they aren’t going to need WebRTC for your living room anytime soon. The main use case of video chat with others is a hard nut to crack in the living room environment.