Nvidia has more or less discontinued the current Shield Android TV hardware and according to Slashgear a new version will be revealed at CES 2017 next month. It will feature improved WiFi and a thinner, bluetooth-enabled controller.
An upgraded Nvidia Shield
A new version of Nvidia Shield passed through FCC in late August 2016 and according to Slashgear the new hardware will be officially launched at CES 2017 in Las Vegas.

It will keep its name and Nvidia will continue to position it as a game console and media streamer. The new box will feature improved 802.11ac WiFi with MIMO (multiple-in, multiple-out) for faster and more reliable streaming. It will also switch from Wi-Fi Direct to Bluetooth LE (low energy) for the game controller that will be thinner and last longer on a charge.
Slashgear speculates that Nvidia will announce support for 4K movies via Google Play Movies at the same time. The current hardware should already be able to support it (it has VP9 decoding) but Shield was not included on the list of supported devices when Google announced the news.
Nvidia’s CES 2017 keynote will take place on January 4. FlatpanelsHD will be in Las Vegas.
- Source: Slashgear