Echoing naznatips, I've seen absolutely nothing over this past year to indicate that the Wii won't follow the same track record with regards to third-parties as the DS. Remember, in its first year on the market, the DS was carried almost exclusively by Nintendo software; close to 100% first-party games, as all the major third-parties focused on the PSP. In its second year (2006), the DS saw a lot more support - Nintendo software still dominant, but down around 70%. In its third, mature year (2007), the DS is now down to about 50% Nintendo software, with third-parties making up the other half. We'll see the exact same thing with the Wii over the next two years:
1st year (DS 2005, Wii 2007): almost entirely first-party (
End of 2008 totals: Wii 42m, 360 24m, PS3 18.5m (made Jan. 4, 2008)