Oh dear. Not the inconsistency 60 FPS part, but using elements from the PS2 when the PS4 is already available is just crazy. I can't believe Sony even allowed this for a franchise that used to be that big.
The article says too the game already have more PS4-next-gen content that any next-gen game released... most tracks and over 500 cars are ready for PS4 already.
About the framerate I said before the game have some drops like in Battlefield 4 for Xbone... the image gets trembling because that in 1080p... 720p is smooth.