I don't usually wade into these speculative product threads, but... I think many of you are looking far down the road into possibilities, which may or may not exist. More immediate, I think the AppleTV needs to have a way to control the other devices it is connected to. I would bet apple will put the talent and technology it acquires into developing an easy, fool proof, multi-manufacturer, compatible way of controlling AV receivers, cable boxes (maybe not this one), dvd players, tvs, etc.
I use a harmony remote, and it works fine, but if you can say, Siri, lets play a game, and it turns on the TV, the receiver to the correct input, etc... Or Siri, can you play this music through the whole house except for the front porch. and it would manage turning on other amplifiers, airplay settings, etc. The hard part will be getting apple to acknowledge that this can't just be a closed eco system, it is going to have to work with other products
I think that is the first step, unifying the control structure of the livingroom/hometheater. Then maybe lighting, but I doubt it. I work a lot with lighting and dimmers and control technologies - new homes that aren't custom won't be built with the new technology (like motorized breaker panels, and central control structures and energy management) 'cause it is too expensive and the average consumer won't know what it is. Custom homes alone aren't a large enough market. Having your control at the end of the distribution (in the bulb, x10 modules, insteon, etc) would require way too many models of product, Apple is about simplicity.
Perhaps there is an iCloud like portal, and some custom libraries that interpet signals from an apple tv into control signals for specific appliances at your house. Those get sent bck to the appleTV from the cloud where they are broadcast to your network aware technology...