What Griffith is trying to say I believe, is that there will be no sound files in the future. The generation of sounds will be completely organic, no samples at all. The software will be inputted with the number of cylinders, firing order, valve timing etc...literally hundreds or parameters that affect engine and other sound generation, then the sound software in the game will generate that sound organically, from the ground up, no samples.
Currently the Viziv and Redbulls are examples of this, but the rest of the cars still rely on samples. Likely only with GT7 will you get the full sound package...if it's fully ready by then. PD is forging new ground in this regard because every other game still relies on samples.