I'd peg Pikmin 3 for 1.6 million myself. It's got a fanbase, but it's not one of their A-list franchises.

Seems about right. I love Pikmin, but it's never been a big seller. 

I hope more people try it out though.

Me too; Pikmin is valuable because it adds the kind of variety to Nintendo's stable that many people claim they lack.

Hopefully by offgering  something different it will attract the kind of people who aren't captivated by Nintendo's more maintream franchises.

Wii U would have to have insanely high software tie ratios in order for some of those games to be near what they sold on the original Wii.  I mean, no, not all 90 million Wii owners bought Smash Bros or Mario Kart, but the 90 million install base allowed those games to have much greater legs and gave them a much larger addressable market than most consoles are used to.  If Wii U sells 50 million, it would be highly improbable that Smash Bros 4 would sell as well as Brawl.  I mean that would be 1/5 all of Wii U owners purchasing it.  Without it being bundled, that is highly improbable.

The New Play Control re-releases, as well as Pikmin 2 Nintendo Select last summer, and the fact that Pikmin 3 will be Wii U's first AAA Nintendo game, I think all three of those factors combine to make Pikmin 3 the highest-selling game in the series by far.  I'd say it could reach 2.5-3 million lifetime sales, because to me it seems like a game that is being built to have legs.  I guess we'll see.

NSMBU will, over time, exceed 15 million. Mario Kart will exceed 20 million.

The only reason I don't necessarily expect NSMBU to also sell 20 million is because I think there will be another 2D Mario game on Wii U -- sans the "New."

I'd love for Pikmin 3 to sell 2.5-3m, but since I expect Wii U to reach 40-50m lifetime in hardware sales, that would require a pretty high attach rate for an game of its kind.

True, it would be an incredible success for such a lesser-known series.  But if my prediction is correct, that Pikmin 3 becomes one of Wii U's system-defining games, it could potentially happen.  NIntendo seems to be putting a substantial amount of time and resources into the game.  They even announced that GamePad photo-taking feature of in-game footage.  Pretty neat stuff.  Perhaps sales at $59 reach 1.5-2 million, then when the Wii U Selects line hits in a year or two, it goes down to $29 or $19.  It could happen.

One thing I think Nintendo needs to do right now if it wants it's software to reach Wii numbers, is ensure that the Wii U has a rousing comeback this Holiday.

I think the best way to do this, is release 299 bundle with slightly higher storage, and NSMBU. That along with a better library, and hopefully unannounced games should do it.

Gamecube sold 21 million units. Mario Sunshine sold 7 million copies on it.

I highly doubt any high number of sales is out of the question.