I think it will do well in Japan but its hardly in the same ballpark as 3DS. It's larger and more expensive. Did the larger format Vita do well in Japan? I think its likely to do ok numbers until a smaller more compact version is produced which will then do significant numbers in Japan.
Again same as other regions, initially there will be strong sales by the die-hard fans but its after this that is more significant to see if it appeals to a wider audience. It also depends on which games come to Switch of course that will be a huge factor in its success or failure in Japan. So there are quite a few variables in play.








