If we go by the previous Pokemon games on DS, they've done as follows:
Diamond/Pearl:
Japan: 1646k
Worldwide: 3491k
(47.1% in Japan)
Platinum
Japan: 992k
Worldwide: 1753k
( 56.5% in Japan)
HeartGold/SoulSilver
¨Japan: 1446k
Worldwide: 2955k
(48.9% in Japan)
To top Black Ops (X360), it needs to sell 5.7 million in total. That would mean 45.6% of its sales would be in Japan. In other words, Black/White would have to have a larger increase upon the previous Pokemon games in the west than it did in Japan. I think that's unlikely. I'd wager this one is going to be closer to Platinum in marketshare amongst the areas, mostly because of how huge it was in Japan, and the launch time in the west.
So, around 4.9 million. Fourth biggest so far (including multiplatforms), and the biggest from Nintendo.
It has a slight chance to become one of the top 10 best selling games of the generation too. That would require around 24 million sold, though, so it's doubtful, but possible.
