Mark(us) Wyndham of "THIS is Markus. You may not know him now but you will someday!" fame. Eventually turned pro for Planet Earth and then just vanished.
Chris Branagh. If memory serves, World stopped giving him ads while they brought on Jovantae, Daewon, Chico, et al and turned them pro, but included his very short and subpar part in "Love Child" along with those guys, seemingly just to embarrass the kid and manufacture a reason to demote him to am rather than just kick him off. Then he either quit or was eventually kicked off, and disappeared from skating soon after.
Coco Santiago but purportedly, he had some pretty serious mental health and substance issues.