Okay... This thread has HUGE errors. I'll try to fix some.
SMG has worse legs than SMS in Japan? http://vgchartz.com/swlaunch.php?reg1=Japan&game1=Super+Mario+Galaxy+-+Wii®2=Japan&game2=Super+Mario+Sunshine+-+GC®3=Japan&game3=&weeks=32
SMS had after 65 weeks in Japan, still sold less than SMG now has after 12!
If it keeps fading at the current rate, I expect it to reach SM64 average and keep on to it. http://vgchartz.com/swlaunch.php?reg1=Japan&game1=Super+Mario+Galaxy+-+Wii®2=Japan&game2=Super+Mario+Sunshine+-+GC®3=Japan&game3=Super+Mario+64+-+N64&weeks=65
Mario is the kind of games that keeps selling. If there are bought 10k wiis, you can trust there is at least 0,5K SMGs sold.
This means that since the Wii will make 120M more sales (my prediction, you can change it if you want) there will come about 6M more sales, even after SMG really has stopped selling.
I predict that SMG might end up selling 15M.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS