Via its support page, Nintendo Japan announced today that repairs for the original Wii console, model RVL-001 (all color variations), will end on March 31, 2020. The reason: difficulty in getting and securing parts needed for that specific Wii model.
Wii owners in Japan whose console needs replacement parts may want to act as soon as possible. Part of the post says that even if required parts run out before deadline, console repairs may not be accepted. In other words, Nintendo will stop accepting repairs as soon as it runs out of stocks.
Nintendo hasn’t mentioned if this will affect Wii owners in other parts of the world.
Users who own Wii models RVL-101 and RVL-201 (Wii Mini) are not affected.
[Source]: Nintendo Japan: Wii本体の修理受付終了に関するお知らせ.