Coming from a Nintendo rep
“Nintendo Switch is a home gaming system first and foremos. We have made no announcement regarding the future of Nintendo 3DS. Obviously with sales of almost 60 million 3DS portables worldwide, there’s still a huge hunger for new games, such as Pokémon Sun and Pokémon Moon. There are many more games in the pipeline.
We have nothing to announce about the production status of Wii U. We announced in April 2016 that as we prepare for the launch of Nintendo Switch in March of 2017, Nintendo will ship 800,000 Wii U hardware units to the global market for this fiscal year. As a result, the inventory of Wii U hardware at retail will become harder to find. We encourage anyone who wants Wii U to communicate with their preferred retail outlet to monitor availability.”