How long can this Cor-ten roof last??

The facts: This Cor-ten Steeltile roof has sustained through perhaps the meanest winter climates in America. At almost 8,000 feet elevation and nestled at the foot of Kirkwood Meadows Ski Area, has endured many winters with more than 50′ of snowfall. Is it the toughest roofing around? We’re open to discussion. Please chime in. Brian