I saw a profile (probably on HN) about how the Siri technology was developed. This service sounds nearly ideal for Siri. In the short term I'd bet 50% of requests could be handled with total automation. Seeing how they add functionality to the system I'd bet they can get that up into the 70+% range over time. Many things still require a human touch, but you can throttle demand with pricing.
I'd expect it to come from Amazon first though. Seems more up their alley.