Amazon has slowly been expanding the circle of devices that can use Alexa Announcements, but now it's throwing the gates wide open. The company has made the intercom-like feature available to any device with Alexa support built-in -- you could use your thermostat or fridge to tell the kids that dinner is ready. In theory, you won't have to visit a specific room like you might today.
The feature requires device makers to implement it, and not every product will necessarily qualify. They'll have to support converting MP3 files 45 seconds or longer to an Alexa-ready format. There may still be gaps in Announcements support even if your home is full of Alexa devices. Still, this could make the broadcasting tool far more flexible in the long run.