Update: Confirmation of Alexa support and a photo of the ecobee4 can be found here, ahead of a May 3rd announcement.
The ecobee4 smart thermostat, originally leaked last month by Apple, has just passed through the FCC. As to what it offers over the ecobee3 and its remote sensors, well, that remains mostly a mystery. We assume it will retain Apple HomeKit integration and there is some thought its profile will match the new and slightly revised ecobee3 lite.
But most curious, based on the FCC glamour shot above, is some sort of round opening along the top of the ecobee4’s enclosure. What I’d originally thought might be additional or relocated environmental sensors, versus an exhaust port, may actually be a small speaker given new intel I have received indicating tighter ecobee+Alexa voice integration. Incorporating Amazon’s voice assistant makes a whole lot of sense given the practicality (why clutter things up with yet another Echo Dot) and recent $35 million dollar investment.