I think this game has a lot of possibilities in Japan .First the PS2 and PSP prequels have met great success .To understand a bit the numbers we can take a look at the PSP version wich sold some 600K in Japan being besides both Monster Hunter the third best sold PSP game in Japan to date .
The PS3 version has great graphics and an online mode and it will appeall to the japanese .We must remember japanese just love golf .
Besides I heard something very interesting about this game .The online gaming is limited to 8 players (fair enough ) but more players can connect to the game and follow the competition and speak with others doing the same .This game has a lot of possibilities of creating a big community around it .
As for sales ....I think it will push the PS3 sales .When this game arrives others as Ninja Gaiden Sigma ,Innocent Life and Folklore will be out already so I count the PS3 base to be over one million .And this game will push some systems too .Having all in count I think 300K would be a good number .But I think this game will have a lot of legs .