First off, love the pictures! Looks great in blue!
To be faster, it will need AWD. The hybrid motors and battery will add hundreds of pounds of weight. Even if they went to a V6 gas engine, which is probably what they should do, that would only maybe cancel out the weight gain. The only way to be faster is to add traction or at least 100 HP. Considering the competition from the Audi A8 diesel and V6 S400 Hybrid, expect the former. Note these options aren't sub-5-seconds fast, like the LC is.
The problem with the current LS600hL is weight. They need to fit a lightweight AWD system, and probably drop two cylinders. How they solve these issues and make the hybrid outperform the standard model should be very interesting.
BD