1: To get a good start of PS4, GT6 is going to make the ps4 a sucess in sales which Sony needs with todays big moneylosses.
2: GT5 is as good as it gets on todays consoles, to get something worth called GT6 it needs more horsepower. PS4 will bring that.
3: Since they starting to talk about GT6 it means we are about 1.5 - 2 years away from the finished game. Perfect for a ps4 launch.
4: With early PS4 launch there is time left in PS4 lifespan to launch GT7 if needed
5: The game needs new incomebase, that means competition with prizes on more regular case than today. For that there needs to be better network and gamestability + rules. PS4 can handle that.
For me this is enough to convince me it is a PS4 title and it should be a PS4 launchgame.
The timing should be perfect too...with GT5 getting its final update + some new DLC to keep fans playing for a year or two.
1) Console sales don't actually help with financial losses when you sell your consoles at a loss. If we look back to the early years of PS3's life cycle, when they were losing at least $200 per unit (depending on whose production cost figures you go with), had PS3 sold twice as well that would simply have meant Sony losing twice as much money from PS3. Fanboys like to argue that "You have to spend money to make money" or "They make it up in game sales", but both arguments hold true whether Sony sold ten million, twenty million, or a hundred million units. The number of units sold doesn't change this profit/loss ratio.
The only way selling PS4s will help with "today's big money losses" is if PS4 sells below cost (profit on unit sales). Otherwise, they're just moving more hardware at more losses, which doesn't help with money losses. "But they can make money from PS4 game sales." Yeah, but they can do that with PS3 game sales, and there's far more PS3 owners to sell them to. It will take PS4 several years to catch up with PS3's current installed base.
2) They don't need to dramatically improve graphics. They can simply improve the actual game, and pack in more content. Forza has more content on Xbox 360, and that's just on DVD.
3) If it's for PS4, it won't be another year and a half to two years. You're looking at
least 2015 if it's a PS4 title. GT6 won't be there at launch.
4) That presumes that GT6 will be there at the start of the generation. I don't see it. Also, it takes PD so long to make a game, even when just basing it on an existing game engine, that there's no way GT7 will make PS4 if GT6 is on PS4, if they couldn't even get more than one full GT game on PS3. "How do you reckon it takes them so long to make a game based on an existing engine? Look at PS1 and PS2!" Yeah, but that was then. Look at how long it was for GT5, and then two years later we still don't have GT6. If they could make a game within maybe a couple or three years when basing it on the existing engine, then we'd definitely be seeing GT6 for PS3 this year or next, but instead we're talking about possibly PS4, which means PD can't base a sequel on a current engine in a reasonable time.
5) This one made my brain hurt. "Incomebase"? At first I thought you meant a source of revenue for PD, but they can get far more money selling GT6 on PS3 than they could on PS4, since PS3 already has a large installed base. Then it sounded like you mean for players to earn credits, but this isn't hardware-specific. NES could offer the player more means of earning credits if you want to make it possible. You don't need new hardware for that.