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The Switch sales are still being constantly sold out despite the huge number of Switches being sold. That is crazy as not even the Wii could do that. It looks like we won't know the true demand in Japan until next year. We are definitely not going to see ample supply this year.
I think launch-aligned Wii and Switch are pretty close. Wii stopped being sold out in its first fall, but Wii also launched three months farther away from fall. Wii had a baseline of around 60k before fall while Switch had ~25k in May and June and later on ~45k; so yeah, launch-aligned the total amount of Switches sold might still be lagging behind Wii.
That being said, Switch is bound to take the lead and afterwards maintain better momentum during its second year. Japanese third parties treated Wii like an outcast, but since then the market has changed so much. Back then there was a choice between Wii, DS, PS3, PSP and 360 (Microsoft was throwing cash around, so it wasn't about installed base alone); now it's only PS4 and Switch.