It is a possibility if they want to maximize sales of the PS3 version this year.
Also on PS4 there's Drive Club this year. But the game is probably multiplatform, so a PS3 version doesn't mean that they aren't working on PS4.
you guys keep putting companies into this small box, and then complain how come they are in the box.
GT6 can be both PS3 and PS4, launch in December, people who dont have money for PS4, will get PS3 version and people who do, will get PS4 and GT6.
Drive Club is different game and launching in September/October.
Sony needs stellar lineup right away if they want to launch PS4 out of the gate and one of the Sony guys said before something like - big difference between PS3 and PS4 launches will be that PS4 will have many games.
Boom. Games. Sell. Consoles.
Artifically limiting your expensive new console to 5 games at launch will not do you any wonders.
And via PS Cloud, they can deliver GT6 PS4 to anyone, PS3 owners, PS4 owners, Bravia Owners, Xperia Owners, anyone.
PS4 version can have more poly car models, more track details, more cars on the track, more physics, more damage... it can easily all be in the same engine, with 2 switches - PS3 and PS4.
This is how many of new games are PS3/Vita - Sony has given them tools to make transition as simple as a switch. Same will be done with PS4, with expection of big studio's doing their own tools.
By having both PS3 and PS4 versions of GT6, they are maximizing sales of both PS3, PS4 and GT6.