It seems PS4 will end selling something like this:
US 38-40M Less than PS2 (around 48M), less than X360 (around 44M), around the same as Wii (around 40M) and more than PS1 (around 35M)
Europe 53-55M Just behind PS2 (around 56M), but way ahead of PS1 (around 37M), PS3 (around 35M), Wii (around 34M) and X360 (around 26M)
JP 10-11M On par with PS3 (around 10'5M), less than Wii (around 13M) and way less than PS2 (around 23M) and PS1 (around 19M)
ROTW 23-25M On par with PS2 (around 25M) and way more than everyone else, PS3 (around 12'5M), Wii (around 9'5M),PS1 and X360 (both around 9M)
Not bad for a console that has spent 6 years or more at 300$ or more. Software is going to be close to PS2 at 1500M too, but with way more profits this gen thanks to DLC's and MTX.
Sony really hit the jackpot with the PS4....