What do you think of other devices Apple would put Siri? iPad?, this is laziness already, the device is in your hands and yet lazy to make appointments? Macs, could be. Like if you're working or composing an email then suddenly pops up on your mind you need to set a meeting with your team or something. Just my thoughts. This source looks like its a chance.
Apple TV, definitely. "Siri, play The Matrix." "Siri, what time is Shrek showing?" "Siri, record Fox at 8pm without commercials."