Compete with the 3ds? In Japan? There's a 3DS for every fifth person in Japan!
Compete with =/= sell more lifetime. I think the Switch will pull steady weekly numbers that are competitive with the 3DS at its current level or higher. Wouldn't be shocked if it beats the PS4 weekly either.
Besides; it's not impossible that it outsells the 3DS in Japan in total either, it seems made for Japan and I think it will be its strongest market by far. It could well end up having 50% of its lifetime sales in Japan alone.
End of 2016 hardware sales:
Wii U: 15 million. PS4: 54 million. One: 30 million. 3DS: 64.8 million. PSVita: 15.2 million.