They will be enough to make PS3 buy worthy, and they will certainly boost PS3 sales to over 30k in the weeks they launch.
How do you know that? PS3 launched 5 months ago, and it still didn't get any real system seller, and there's almost no new software released since many weeks. Last game was Konami's Baseball (bad, bad game), and this week Tokyo Racer. Last real game launched for PS3 was Gundam Mosou. It did boost PS3 sales to 40k from what I remember.
The system has no definition in my opinion. There are no new releases, and SONY doesn't help themselves by releasing gimped versions of their big sellers (MotorStorm, F1). To guess the outcome of PS3's success in Japan, we have to wait until it's situation gets stabilized.
When, like some of people here said, big games like Mina No Gold, NGS, MGS4, DMC 4, RE5, FFXIII won't boost PS3 sales to 20-30k a week, then we can say that it's too late for SONY in Japan.
VF5 was never a great selling game. Gundam did sell alot considering the size of user base, and it did bump PS3 sales. I'm not saying that after launch of 1 of the games mentioned by me, will suddenly make PS3 sales sky rocket, I'm saying that it will bump PS3 sales, and once good software starts streaming in, PS3 sales will go higher than they are now.