I would love to see a wireless, that is a battery powered, Wi-fi switch that paired with another wired smart switch.  Think of the possibilities:

* A switch added to a location that was never wired.

* A three way switch without travelers.

* A four, or more, way capability for 3-way switches.

I'd link you to a Leviton example of exactly that but such links aren't allowed.   Just search "Leviton Anywhere Companion" and you'll see an example.

Thanks!

-d