PD has options.
If GT5 used some sort of standard encryption system universally used on the PS3 and presumed to be good at that time, then crack one, crack them all. (I think that is what happened to GT5...)
If they go their own way, it will be much more difficult to crack. The question is just how far do they really need to go to stop cracking GT6 and how willing is PD to go there?
PD / Kaz is good at obfuscation around details, so I will wait for real news about the sounds. They know it bugs us, so maybe he's just pushing some of our buttons.