We guess perhaps that was Google’s way of encouraging app developers to adopt the feature in hopes of boosting Chromecast sales and support. However according to a report from Android Police, it seems that Google has quietly started to roll out an update for the speakers that will enable Bluetooth streaming.
Note that Google did announce at I/O earlier this year that the Home would be getting Bluetooth streaming support, but there was no specific dates mentioned as to when this update would be available. We’re not sure how widespread this update is, so maybe you should check your Home app to see if there are any updates for it.
By enabling Bluetooth streaming support, it will help make the Home speakers gain a few more customers, especially for those who might be using apps that do not support Casting. Plus it will make the Home a bit more user-friendly since Casting will require an internet connection for most apps, so with Bluetooth streaming there is at least the option for offline use.