All you have to do is look at shadows in GT6 to see that something has been shortsheeted in order to do what has been done in the new engine. In some cases, they're worse than GT5's shadows. Much of that is due to the ram available, as shadows are basically textures, I was surprised to learn, and good shadows require a good amount of available ram.
Some things should be available to add in to GT6, like a Livery Editor. Make our liveries collapse to a texture skin, and they're no different than any skin in the game. Other things like a damage implementation on the scale of Codemasters or Turn 10 is a lot less likely, but who knows? Kaz has said that they're working on things for GT6 add ons he can't even discuss yet, so I wouldn't say no to any possibility right now.
But as some others have said, when Gran Turismo hits PS4, I expect to have a truly cinematic experience. Graphically, overall, some improvement. But in details, I expect huge advancements. Fantastic lighting. Realistic shadows. Worlds with all kinds of lifelike properties, such as crowds that behave like a mob of people rather than obvious clones acting repetitively. Flags and trees moving in the breeze, and a breeze that changes dynamically. Precipitation that puddles and pools, and evaporates unevenly. Dirt and snow that ruts realistically. Dirt and mud that accumulates on cars in a lifelike way. A good visual and mechanical damage build. A proper Livery Editor. A massive Course Maker. And who knows what else?
