[WorldMaker]

It depends on how much power it consumes, doesn't it? Phone hardware has been doing very low power voice-wake-up for a hardware generation or three already. It's part of the argument of why "Ok, Google", and "Hey, Cortana", and "Hey, Siri" are so long (and somewhat unwieldy when said often) as standard wakeup phrases to both avoid false positives and lower power consumption for passively listening for a wakeup keyword.