I presume you have no idea about what you're talking about
60 million investment has already been paid in advance by worldwide sales of GT5: Prologue and GT PSP.
Taken that into account, all revenue from GT5 will be pure profit for both SCE and Polyphony Digital.
Numbers:
http://www.polyphony.co.jp/english/list.html
Average GT5: Prologue price - 20$ (started as 40$ - notice that prices in the world differ, in Europe Prologue made almost 2,8 million in sales with the price of 35 euros = more than 45 $) x 4,7 million = almost 100 million $ in revenue.
Mind that good percentage of Prologue sales was made via PSN as digital download, where there is no costs such as "normal game" - but with the same price - so actual profit rate from each game is much higher.
Average GT PSP price - 20 $ (everything same as above) x 1,8 million = 36 million $ in revenue.
Combined 136 million in revenue. Now presume that Polyphony Digital has pretty much unique status in SCE, they probably have special treatment regading licencing, development tools and such, and they probably get enourmous amount of revenue as their profit.
Notice that whole development of Prologue is actually the part of 60 million of GT5 budget, while development of GTPSP probably costed just a tiny fraction of the budget becuse all assests were derrived from GT4 and all PSP engines and libraries are on PD's disposal for ages now.
In conclusion, every Gran Turismo game so far was already payed-off with its predecesstors and you really do not have to worry that Kazunori or Polyphony Digital will EVER become short of moneyz.