I'd say about four hundred million billion. That's what the figures seem to suggest anyway.
It's hard to predict when you don't know if this is the 3DS successor or not.
It has to be..... not even nintendo are that crazy (to do another handheld, after it being the main draw of the switch).
I suspect what will happend is there will be a tablet only version (without the docking part) that costs like 199$.
Then the controller base + dock will be additional 50-100$.
Or a bundle where you get all of that for 249-299$.
Assumeing the Nintendo Switch is the replacement for the 3DS as well as the Wii U.... how many do you think it will sell?
Necro-bump this 2020: http://gamrconnect.vgchartz.com/thread.php?id=229249
Bumb in 2021: http://gamrconnect.vgchartz.com/post.php?id=9047071