The change "will break IFTTT," Chandra said. You couldn't use the automation service to automatically turn up your Nest thermostat when you get home, for instance. Google Assistant's routines are intended to fill the gaps, but this won't help if you have a device or functionality that routines won't address.

These kinds of changes aren't always avoidable, and might be important when smart home privacy is becoming an important issue. Even so, this underscores the instability of smart home tech at this relatively early phase. Like it or not, you're at the mercy of evolving standards that could potentially limit the usefulness of your devices years down the road.

Update 05/07/19 8:01PM ET: Based on an email IFTT sent Nest will be retiring its Works with Nest program on August 31st, 2019. Nest Thermostat, Protect and Cam will all be affected.