Mario Kart Wii should be at around 30 million. Its sales so far in 2011 are quite disappointing. YtD sales for Mario Kart Wii:
2009: 1311k
2010: 749k
2011: 606k
In 2009 it sold 7376k, in 2010 it sold 5164k. In both '09 and '10 it sold around 15% of its total sales in the time up to now (17.5% in '09, 14.5% in '10), which means that we can expect it to sell around that this year. That results in 4000k for the year, or 3.4 million more, which results in 29.9 million by the end of 2011, and a tad over 30 million by the end of January 2012.
New Super Mario Bros. Wii is likely to sell less than 4 million this year, as it's already trailing below Mario Kart Wii. Let's say just 3 million more for NSMB Wii, which results in 24.5 million.
They should both be heavily outsold by Wii Sports Resort which is likely to sell over 8 million (possibly over 9) in 2011 and overtake them both in lifetime sales, as well as possibly become the third best selling game of all time by the end of January 2012, second to only Wii Sports and Super Mario Bros.
Wii Fit Plus also has a decent chance of beating NSMB Wii by the end of January 2012.
I'm not sure if New Super Mario Bros. Wii will ever manage to overtake New Super Mario Bros. DS which is actually selling exactly as much this year as it did last year. It should manage 30 million lifetime, which is roughly where NSMB Wii might end up.
