Here are my predictions:
Wii: 9 million (although I think the holidays will be huge once more with great $99 bundles)
X360: 15,5 million (the Wii peaked in 2008 when it was available in its 3rd holiday season; I think the same will happen with Kinect)
PS3: 14 million (I don´t know why, I just see it slightly under the 360)
3DS: 20 million
Vita: 9 million ( I don´t think Sony are willing to cut the price, so it should have a rough 1st year)
WiiU: hard to say right now. Baring in mind that it will probably launch between Sep-Nov at a (too) high price point, anything from 1,5-4 million seems possible for me. I´ll let Seece decide if this counts as a preditcion :D
Overall, I think 2012 is very hard to predict. Even if WiiU delivers the "full package", it might still have low numbers at a high retail price. Vita is hard to predict because as far as we know, Sony cannot afford to cut price but they still might. And trhe current HD consoles might have yet another peak year or start decling. Wii should continue to decline rather heavily, but no one knows what a RRP of 99$/€ could do on Black Friday. In other words, my predictions may be off I don´t want to look back in in 10 months.
Maybe I´ll add some SW numbers or pricecut predictions at some point.