There will never be another moss, campbell, or any of the "supermodels"
That was a freak occurence. It was a combination of a lack of glamourous celebrities in Hollywood at the time, a decade of excess and a few very influential designers. No matter how big or successful models of today become, they will never reach that level of celebrity...because that is essentially what those girls became, they became celebrities. The one person who might have had that level of fame was Natalia Vodianove, pre Calvin contract of course. She was literally an overnight sensation. She had a story, not an editorial, an actual story devoted to her in US Vogue, not to mention becoming the darling of the fashion world...but even still, she never would have been as big as say, Linda Evangelista. That era is gone, never to be seen again.
Edit: I also agree with what wyatt said about today's models treating it like a career.....that also plays a big part in why there will never be another age of the supermodel.