Well, it's not for me to get shirty, but Skylines have, and will continue to be saloon and coupe cars... Always have, and always will be. The GT-R you talk about, (not the current one), have always been the range topping variant. A bit like the AMG to Mercedes, and the M-Power to BMW. The rest of the range has had engines ranging from 1.6 litre, to 3.5... So, Skyline itself is just the name for a a range of largish cars made by Nissan/Datsun, going back to year dot. The G35 does 60 in around 5.4 seconds, so certainly quick.
The "new skyline" is not a skyline at all. it is a completely different model, (although the Altessa awd system is used in the G35X, the awd varient of the Skyline, and the same system used in the GT-R's in the past). It's like calling the Porsche carrera GT a 911...
By the way, the Skyline was introduced at the same time in 2001, so who uses which bits off what car? Does that make the 350Z not actually a true Z car, as it uses bits from a Skyline?