Several problems: 1) Powerline is power hungry. A Devolo adapter for example eats 5-10W. Multiply this by the number of smart plugs or switches you use and you might end up with a sizable electrical bill. This would also mandate relatively large chassis. 2) There are at least two competing, and incompatible, PL standards: HomePlug AV and G.hn. And in theory there would a another standard specifically for IoT/home automation-devices. Which one would you expect to be implemented?