Quite possible.
Another thing of note is that Wii's lifetimes sales have surpassed the GameCube's lifetime sales in both Japan and Europe this week. It's a few months away from the N64 in both territories (1.3m Japan, 1.9m Europe), but it has a good shot of surpassing the N64 in both territories before the end of Q1 2007.
In America, Wii catching GameCube sales in the first quarter is unlikely (behind 5.4m), but it should be able to reach GameCube's worldwide sales in the first quarter anyway on the strength of Europe and Japan. Pretty impressive.
And the DS should beat the NES' lifetime sales in two or three weeks. Nintendo's gotta be pretty happy with themselves.