http://www.techradar.com/news/well-be-waving-goodbye-to-the-wii-shop-channel-in-2019

Nintendo has announced that it plans to close up the Wii Shop Channel on January 31 2019. After this date it’ll no longer be possible to buy titles or applications from the channel for either the Wii or Wii U consoles.

The process of closing up shop will actually begin before then, though, as from March 27 2018 users will no longer be able to add Wii points to their account.