Gameplay trumps graphics. I see little hope for PS3 in Japan. FFXIII will help but it will be a temp boost and then a downfall like when previous boosts have occurred.
Mil. Sellers:
Wii: 25 titles 101.4 mil total avg 4 mil per title
PS3: 14 titles 28.6 mil total avg ~2 mil per title
360: 41 titles 89.8 mil total avg >2 mil per title