Yeah, thinking about this a bit more, I guess it is that the voice processing is done in the X1 box (or back in the comcast home office cloud in fact), which cannot command the remote to talk to the TV. Clearly the channel changes are happening in the X1 box.
I don't know the capabilities of HDMI enough to speculate whether the X1 might command the TV (via the HDMI cable) to change volume or turn itself on/off. Perhaps someday, and that is where the 'yet' comes from in the message.
... View more