Depends on price cuts. Assuming all three major consoles get price cuts of some sort:
1. 3DS
2. PS3
3. 360
4. Wii
5. PSP
6. DS
7. NGP
This is based off the current sales trends of each console so far this year, combined with the upcoming line up of each console. Essentially, I expect the 360 and Wii to slowly trend downward over the next two quarters (until the release of Gears 3 in the 360's case, and until the holidays in the Wii's case - barring any surprise Nintendo releases), while the ps3's sales will be sustained via Sony's strong first party line up. I think it'll trend downard to a degree, but not as drastically as the others. Overall sales should be pretty close between the three.
Then there's the variable of price cuts. I expect all three consoles will get price cuts between Q3-Q4. It may actually be whichever price cut comes first that decides this threeway race.
Speaking of price cuts, the effectiveness of the PSP's price cut combined with the waning sales of the DS in a 3DS world will determine which of those two sells better for the year.
I'm also assuming the 3DS will retain the popularity of the DS. For all I know, the high price point and it's initially small library could inhibit its sales somewhat. I think 10 million is guaranteed, but how the public reacts to these factors will determine if it can get closer to 20 million.
