I don't understand.................they go hard [easily as hard as most modern cars], they have all the fruit - abs, climate control, power eveything etc etc, they have one of the biggest after market support bases so you can get just about anything you want, they still look absolutely the best [i actually hate the modern all angles and sharp creases], they are as or more reliable than a modern, tuned right you get over 500km out of a tank on the highway [and pushing 280+rwkw], they pull crowds like free plasma tv's, they handle as good as anything out there, if you write it off [prang, stolen, fire] your only down $15K and a good cry, and the list goes on............why would you want to sell???
At the present rate I reckon it will take the rest of the car industry a couple of light years to catch up. The only threat to the skyline market is the new GTR. Once it becomes s/h and cheaper, it will overtake and out strip the market [trust me I've seen this with other makes and types], but that is at least 10 years away.