I see a few possible advantages, and some other features they could bundle in, although we may not see all of these in version 1.0.
- No yelling across the room at your phone. You could have one in multiple areas of your house and anyone could access them, not just you with your unique voice print.
- They're always connected to your home and could act as HomeKit relays to areas of your house where accessories are out of bluetooth range. You don't have to buy an Apple TV to act as a HomeKit hub when you're away.
- They could contain WiFi hotspot functionality and multiple units could function as a mesh network, which is much more efficient in covering homes.
- They could potentially act as wireless charging bases—either through direct contact setting your device on top, or by having a device nearby one if they go the true wireless route. I could see them implementing the former in this version, and true wireless in subsequent versions as it seems Apple is ditching those plans this year due to whatever issues they're having.
- They could act as a high quality, whole home speaker system.
- They could potentially house an array of sensors from motion, to temperature, humidity, air quality, etc that could be used as HomeKit triggers for other devices.
- "They could act as a high quality, whole home speaker system."
- There are rumors that the next Echo devices will have a home intercom feature plus Sonos speaker integration.