Nice theory. I think that has something to do with it. But I'd also add that the actual content of these games is what keeps them selling. As well as positive word of mouth, which imo has always been the best and most effective form of marketing there is.
I mean, if you look at the titles that are of ever green status or hitting the 10m+ mark: Kart, WSR, NSMB, Wii Fits, Brawl (soon) there are A LOT of content in these games. The selling point for these games aren't their graphics it is in the content.
Also people like ot say Nintendo milks franchises but, rarely do you see more than 2 iterations of a franchise in a gen. More often its just one game per gen (Brawl, Kart etc) Where as other companies pop out franchises yearly (GH,COD,Madden etc)
It also has to do with the console itself which sells like an evergreen title. During historically slow months Wii continues to sell at a brisk pace. When you are selling that many systems you are bound to sell large amounts of software as well.
Bet between Slimbeast and Arius Dion about Wii sales 2009:
If the Wii sells less than 20 million in 2009 (as defined by VGC sales between week ending 3d Jan 2009 to week ending 4th Jan 2010) Slimebeast wins and get to control Arius Dion's sig for 1 month.
If the Wii sells more than 20 million in 2009 (as defined above) Arius Dion wins and gets to control Slimebeast's sig for 1 month.
