Google has announced that all Wii YouTube support will end on the 30th June 2017. Not only will support end but the application will be sunset meaning you won’t be able to keep using it as is, it’ll just not let you watch videos anymore.
After 30th June 2017, the YouTube app on this device will no longer be supported, but you can still access YouTube in many other ways. A list of supported YouTube devices is available youtube.com/tvdevices
The issue appears to be the video sharing company moving away from Flash based apps and switching to the HTML5 versions instead. That means you can still continue to watch YouTube on the following consoles PlayStation 3, PlayStation 4, Wii U, Xbox 360 and Xbox One. A Switch version is in the works also. Of course you can also use web browsers, mobile devices and Smart TV’s