The other thing to think about is...the next generation of race based kits will be designed around a mixture of both nimh and lipo weights. If you run a lipo with no ballast, the car drives like crap....a heavy car drives a million times better....even a 6C with extra weight feels nice to drive.
So, companies like AE, Losi, Kyosho, Academy etc will knowingly take into account that within a year or so, Lipo will be acceptable for all forms of racing. Therefore, the next step in chassis design will be a car that can run light and "feel" like it's heavy.