Aielyn on 04 June 2013
1.5 million by year's end. Closer to 4 million lifetime.
In case someone's wondering, I think it'll be subdued amongst titles like Pokemon X/Y, LttP2, and Mario Golf, and will end up being a game on people's "Catch-up" list for early 2014. That, in conjunction with it being earlier in the 3DS's life than Bowser's Inside Story was in the DS's life, means I expect slower early sales. BIS managed about 2.2 million by end of 2009.
