It was bound to happen. Wii slows to halt by year 5.
The lack of support from Nintendo as they shifted to Wii U prematurely killed it.
I think it would have been better if Nintendo continued supporting Wii, and perhaps released a Wii HD model in the interim, prior to the Switch. While some might call Wii U a Wii HD, it wasn't at all; it was a much slower console due to the really poor OS they gave it, and it required a "Wii Mode" in order to play Wii games, also the really expensive Gamepad controller.
If there is one place Sony consistently beats Nintendo at, it's generation transition.
I describe myself as a little dose of toxic masculinity.