According to the report Nintendo has already stopped production on the console’s accessories with inventory expected to be depleted by the end of the year. Wii U is said to follow suit by the end of the year.
Note that while production may stop, that doesn’t mean Wii U will be removed from shelves. There is still plenty of back stock that needs to be pushed through as well.
This isn’t entirely shocking as Nintendo is planning the release of their next console/handheld hybrid set to release either this year, or next. You can find out everything we know about the NX here. The NX is rumored to have a handheld portion released by the end of the year, with a console version expected to release next year. Nintendo also noted that more details and information regarding NX will be released throughout the year.
Currently Nintendo has not put out an official statement regarding Wii U production.