Michael Pachter says Wii U to sell 20 million units worldwide

[Soundwave]

Actually the sales gap is worse than I thought ...

GameCube shipments through September 2004 (which correspond to Wii U's September 2015) are 15.97 million:

http://vgsales.wikia.com/wiki/Nintendo_GameCube

The Wii U is maaaaaaaybe at 11 million shipped at best? That's a 5 million gap, so the Wii U at its general sales pace is more like 1 1/2 years behind the GameCube now.