Mention of Jason Brown brings up an interesting thought. It seems that "natural talent" means physical capabilities in most cases. But with Jason it also means natural performance abilities. Nobody can learn the level of perfomance skills. And as I've read different places, he works hard so that he can consistently display his natural talents. Seems like you really need three things (two kinds of natural talent plus work ethic) to be a well-rounded successful skater.
That makes sense. And I'd add one more trait: the ability to perform under pressure. Having a cool head is a factor that separates "How wonderful he/she is!" from "If only he/she could do in competition what he/she does in practice." I don't know how much of that trait is innate and how much is learned, but most great skaters have it: YuNa, Michelle, Tara, Boitano, Witt. Some other skaters are (seemingly miraculously) able to summon it up at a crucial moment, for example Paul Wylie, who before the 1992 Olympics was known as a head case. He sure wasn't a head case in Albertville.