20 Million is impossible for manufacturing reasons I think. They currently have capacity to fit ~1M systems a month together, which would not be enough. Also IF they DO sell at 1M a month for the next few months, then they will probably run out of chips to put in the system, and its hard-to-impossible to get more chip fabs to make them in the short term, that's out of Sony's hands, even AMD's.
Remember they expected to sell 5M worldwide by march. That will be met later this month , somehow demand is MUCH greater than Sony predicted. I still believe they should not have launched in any Asia territories till Feb or later, when demand from NA/EU is less than 1M/month. You hear people say they bought an X1 because there were no PS4's available.
I think around 14M by end of 2014 would be more realistic.
PS, PS2, Gameboy Advance, PS3, PSP, PS4, Xbox One
