The next big step will be for the very concept of the “device” to fade away. Over time, the computer itself — whatever its form factor — will be an intelligent assistant helping you through your day. We will move from mobile first to an AI first world.
This would mean that AI interfaces — which in most cases will mean voice interfaces — could become the master routers of the internet economic loop, rendering many of the other layers interchangeable or irrelevant. Voice is mostly a novelty today, but in technology the next big thing often starts out looking that way.