I write this in another thread
"First Gran Turismo game came out December 23 1997, and I was thinking maybe next DLC will come around December and include the GT original tracks to celebrate anniversary.
Just a thought I had "
This is what I'm hoping to see too, though it may have to come in stages. The entirety of the GT5 Prologue update was 1.7GB if I remember right, which had 37 cars and the High Speed Ring track, along with some new music and a physics update. So the Classic Tracks, which I hope to see ALL of them eventually, could come in a three or five track download. Though along with them, I would like to see some new cars and new features added to GT5.
The Ferrari F50 would be nice, though I want to see the 355 Challenge too. And I want to see Racing Mods to many of the Ferraris, Lamborghinis, Ford GT and other supercars. But I don't want the rest of the garage to be neglected. Hatchbacks like the Civics and VW Golfs, the Minis, as well as the Mustangs and Vipers... I want to see many more cars added as Race Moddable cars, and with more than one simple livery template.
I also want to see more racing liveries for the existing race cars. And guys, these would be skins, easy to make, as would more Race Mods for us.
I'm hoping they can make an update which improves the physics even more, as well as the graphics, and adds tremendously to the A-Spec races. At the very least, I want to see an Event Generator tool which allows us to make single races or entire championships, both off- and online, complete with rule restrictions, bot difficulty levels and prizes. A "co-op" race which lets us flesh out a field with bots when we only have two or five friends to race with, or however many, would be a fantastic addition.
Whatever the DLC will be, who knows. Other than the Scion.

But I'm hoping to see a few of these bullet points in the Christmas "gift" to us from PD.