I'm going to make a prediction today.  Wii U will sell (at least) twice as much in 2014 as it did in 2013.

Last year:  3.23 million units.

This year:   > 6.46 million units.

Am I an oracle?  Am I crazy?  You tell me.

Seems about right. It's early year baseline is about double and their are some genuine system sellers this year. I think it will be closer to three times as many.

Will be higher than 2013, because Mario Kart and pricecut.

Actually, I think 2014 is gonna be the peak for Wii U. Wouldnt at all be surprised to see 6-7 Million.

Is that a good thing? I'm intrigued 

It's definitely possible. The software library is larger now than it was last year, and we're getting some pretty significant games (MK8, Super Smash Bros.) this year.

For me, Wii U sold 8/9 milion!!!!!
In the end of 2014, sold in tot 14/15 milion.

well, compared to Wii, not even close.

Are we talking fiscal year (April 2014-March 2015) or calender year? I do believe Nintendo could double their sales of Wii U in fiscal year 2014/15 compared to fiscal year 2013/14. That would mean at least 5,6 million systems sold in this coming fiscal year.
However, I find it hard to believe Wii U will double its sales for calender year 2014 compared to calender year 2013 because sales so far in 2014 are simply too low for such an achievement, even though they are about 14 % above the previous year at the moment.

My sale prediction for Wii U is as followed

Calender year 2014
Q1: 900 000
Q2: 900 000
Q3: 900 000
Q4: 2,7 million
Total: 5,4 million

Fiscal Year 2014/2015
Q1: 900 000
Q2: 900 000
Q3: 2,7 million
Q4: 1,2 million
Total: 5,7 million

of course not

i expect growth YoY but double seems too high to me. 3.23

mario kart is a big game. ..the gaps between releases are even bigger.