What comes after mobile payments? Amazon is placing a bet on voice-payments. The Echo can sit in the corner of your family room and order you anything from Amazon just by talking to it.
But just be clear on why Amazon would want to build something like this. Amazon doesn’t want to be a destination anymore; they don’t want to be something you have to go to; they want to be ubiquitous. They want their store “front end” to be floating in the ether all around you, just waiting for you to open your mouth.