That's the thing: Does the GTR need to be so big? The 911 has more space in the back for passengers, okay it loses out on the boot space, but it's not like it's not tourable. Even things like the 488 have more than enough luggage space, so really could it not be shrunk to lose the weight a bit without going gung-ho on carbon and watching the price skyrocket?
Even a boggo C4S weighs 1545kg, and that's got the 4WD/4WS/2+2/6cylTT engine etc. I'm not saying it's remotely comparable to the GTR in anyway (indeed, no-one looking at either car would be considering the opposite most likely!), but it does show that you can do all that without going mental on weight. If they could do the R36 with the hybrid stuff and keep to 1700kg then that would be a success, but then how much more power does it need? Would it really be that much quicker, and would it not then be priced well and truly out of the hands of the ordinary person?