Some of you guys are seriously making mountains out of mole hills.
God of War II was released in 2007, after the PS3 was released, and everything turned out just fine.
I'm sure GT6 will do just fine and won't hinder PS4 sales.
Early ps3 systems also had BC.
Ps4 does not. Going to have to keep both ps3 and ps4 hooked up to your tv...