The Amazon Fire TV Stick 4K has just been announced. It may be able to deliver HDR10+, as well as Dolby Vision, in order to stream content. Amazon has also included object-based Dolby Atmos surround sound, for material that supports it. At just US$49, it may be a significant problem for the upcoming Chromecast update.
https://www.notebookcheck.net/Amazon-Fire-TV-Stick-4K-this-affordable-streaming-device-may-challenge-new-Chromecast.336866.0.html