The answer is imo not totally related to games.
PS3 has seen the release of Minna no Golf 5, Dynasty warriors 6, Winning eleven 08. These series hold 8 spots in the total Japanese top 20 PS2 gameslist. These are very big games in Japan.
The only games bigger than those games are Dragon Quest, Final Fantasy and Gran Turismo (in that order).
So will FF13 and GT5 boost sales: absolutely, but I don't think it will lead to sustained Wii level sales. MGS4 won't do much. The game it self will probably not sell over a million, so the expected hardware boost will be around 300.000 (very good, but not a real saviour).
I think Japanese just don't like the realism of the HD games. They're into manga's, JRPG's, Pokemon etc. The PS3 and 360 focus very much on real life graphics, which I think is not suited for the Japanese market. Sony really focussed too much on the Western market, taking Japan for granted.







