your mother, If there's one thing we've learned in the past 6 months it's that there is no such thing as brand loyalty in Japan, otherwise the PS3 would be doing swimmingly.
I tend to agree with your other points though. There is a slight (and highly unlikely) window of opportunity for the 360 to do something against the PS3 in Japan. The more games that go multiplatform (PS3 - 360) then the better it looks for MS.
They are both clearly on the wrong side of Japanese gaming trends though.