If you look at hardware sales dating all the way back to the NES days....all the way up to current gen... Japan always accounts for aproximately 20 Million hardware sales.
http://www.vgchartz.com/analysis/platform_totals/
NES= 19.3 Million sales
SNES+Genesis = 20 Million sales
PlayStation+N64 = 25 Million sales
PlayStation 2+GameCube = 27 Million sales
PlayStation 3+Wii = 22 Million sales
Now Wii U is not even at 1 million sales in Japan. PS4 is set to come out with a ton of momentum. Final Fantasy XV and Kingdom Hearts III have been announced and will be huge in Japan. Metal Gear Solid V will be big in Japan and will come out soon after launch. Sony's JapanStudio is making a comeback (Soul Sacrifice,Knack,Puppeteer,Rain,Gravity Rush).
Sony is in prime position to take back Japan. It looks like there's a good 20 million sales left for the taking in Japan.
PS3 has sold 9+ million in Japan, and we all know it was extremely expensive in Japan and was overwhelmed by the original Wii when it came out. This time around Wii U has failed to take off and Sony isnt facing much competition in Japan. Plus the console will be much cheaper from day 1.
I think PS4 can sell atleast 15 million in Japan.... maybe even 18-19 million.
