They were able to upgrade the base to 16.04 circa OTA-6/7, and are still releasing updates to this day, with the latest release being OTA-9.
They even were able to fix the camera viewfinder freezing on the Nexus 5! (My main device)
If you wanted to see what they have been up to for yourself, you can visit https://ubports.com
Welcome to your niu world ! We are a cute and loving international community Ｏ(≧▽≦)Ｏ !