I think we can all agree here that handheld gaming devices are super popular in Japan and if my statement does come true I hardly think it will be a shock to anyone. But more important Is what effect will this cause. Will it mean the Switch will get a lot more 3rd party support from Japanese developers than the Wii U as well as even exclusives like Monster Hunter (which wouldn't exactly be a shocker either considering the 3DS). What else will it cause? Contribute to overall higher sales than the Wii U globally? (Especially considering Japan accounts for 22.40 million of the 3DS's sales) Just something interesting to think about what effect the Switch's Japanese sales could effect the system overall not just in Japan but on a global basis.
EDIT: Just thought I would include this as it's pretty relevant to the topic:
PS4's Japan sales number's: 4.34 million.
3DS's Japan sales number's: 22.40 million.
Wii U's Japan sales number's: 3.32 million.
(Stats used are from VGChartz sales numbers updated as of 18th of Febuary 2017)