Chromecast was a successful product. It easily allowed users to stream their content to their tvs and the best part was that it costed only $35. However, in 2016, it is a shame for streaming device not to support 4K especially when you consider the price drops we have seen on 4K TVs lately. According to the reports made by AndroidPolice, Google is working on a new Chromecast named Chromecast Ultra which will come out alongside with Google Wifi and new Pixel phones.
Chromecast Ultra will differ from the current generation as it will have a support for 4K although it is unknown if it will come with HDR support or not. Other than the 4K though, everything will be same. Also, one other difference is its price. It costs $69, a lot for a chromecast but not much for a 4k streaming box at all.
Also, it is not supposed to replace the current generation as it will be another option for people who demands for 4k.