A version of the Google Chromecast dongle has surfaced at the FCC, with support for bluetooth. The FCC is the American communication watchdog, which has to test products before they can or should be released on the market.
Chromecast with bluetooth upcoming – rumor
Google may be working on a new version of the Google Chromecast, this time with bluetooth support. This is evident from a document from the FCC the American communication watchdog that must test products before they can be released on the American market. The current version offers support for bluetooth low energy, but that is not the traditional version of the connection. The required radio for this is added to the new model; otherwise nothing seems to have changed.
That means that support for bluetooth can not be released via a software update. So if you want a Chromecast with bluetooth, you will have to purchase a new model when it is available. The advantage of the Bluetooth connection is not immediately clear. There may also be a new remote control or controller that can connect to the media player through the connection. But that is bad speculation at the time of writing; Google has not responded to the rumor.