I think weight is where it can possibly be at this time, very much diminishing returns. It is easier to add power, but that is reaching its limits too in my opinion. So, what left:
- Hybrid technology for increased burst of power, different drive configurations and increased efficiency.
- Serviceability and reliability. I think the GT3 can use a significant "upgrade" in serviceability of its components from brakes, engine, chassis, and suspension
- increased driver functionality. I would love to have a GT car that gives me more control with its electronics and functionality configuration. Imagine if came with a comprehensive data logger.
- Ease of personalization. You can re-tub a Cup Car. It would be interesting to have such an option for a GT car with different tub options, getting creative would be pretty nice option. Also, if we had the option of choosing our coilovers, diff setups, wheel/tire combinations, etc. (tall order to manage such an options catalog, no doubt, but each GT might become a unique car in its own right, similar to what you can do with a Harley for example).
- If we can have warranty on this type of a car for the street, I think there may be an option to offer (for additional fee) a warranty for trackers.
Increase value offered beyond the basics of power, handling and overall performance. I don't want to end up paying $250K for a regular GT3 in 5-10 years, so value to me is added functionality while keeping prices at time-period-adjusted reasonable levels.