Most likely, it's not going to come out for a while... maybe not expected until April.. even in Japan as you see the fourth stage isn't done yet either (Not saying that every stage, they make a new game...) But I'm sure they wouldn't just update to V4 just to add a FEW, VERY FEW new things into it... It could be also after the rumored 5th stage, if it comes out, because I'm doubtful that Takumi will beat his father before this season is done... I mean... the whole thing is about winning all of his races and to finally take on his father's name...
Unless there's this part after the God battles where Bunta comes to the venue and challenges Takumi and they have a season finale battle... Which would be really cool, but a bit dissapointing since IniD isn't going to continue on... I mean, after Bunta... who else is there to beat... Keisuke after ProjectD??? Or will that be the season's finale? (These aren't spoilers, just incase... Just assumptions... >_>)