I think there will be no patch with "new" sounds...
Guys let´s be serious here, the current sounds should be eliminated from every car...they have to change every one of them and put the real deal instead. With the amount of cars that we have, it will be impossible to do in a year or so...only if all of their team work in them...and even if they have plans to do something like this...which I doubt.
After the leaked info about GT6 and the videos (I will get Anniversary Edition day one by the way) I just give up with the idea of a "holy patch" that can save and please our ears with real and accurate engine sounds...the soul of any car.
I will try to not fall asleep at Nürburgring as happened a lot of times in GT5 though...
Thank god I´m not a guy who plays just one thing...I have a lot of simulators on PC and racing games overall...Assetto Corsa and rFactor 2, Simbin with its games and others are doing a great job in the sound department, and I can enjoy them when I stop playing Gran Turismo...if only PD sort this..."problem"...the game will be much better and more enjoyable for sure.
Gran Turismo 7 can be the one who changes this...imagine a Ferrari sounding like a Ferrari...a Mustang...etc...
Incredible that we are asking for something so basic in any racing game...the engine sounds...