I think Japan and Europe will each get at least 1 million units before the year is out. Nintendo stated that they expect to ship at least 4 million before January. That accounts for 1 million in Japan, 1 million in Europe and 2 million in the US.
Back on topic, Brain Age 2, NSMB, AC:WW and Pokemon Diamond/Pearl should all reach at least 3,500,000 by the end of the year in Japan. Pokemon possibly 4 million if if stays the same speed it's going (in fact, I predicted this speed a while back just before its release).