Keep in mind Canon seems to be supplying only the color ratings right now (whether that means B&W and color are the same or not remains to be seen). While UltraSmooth Fine Art is indeed rated at >205 years for black-and-white prints, it's "only" rated at 108 for color. The color K3 print still edges out the comparable color Lucia print by a few years, mind you, just not to the same extent as the 200 figure.
Curiously, Canon provides a separate B&W rating for the fine art paper in their own testing, but only provides a single rating in the Wilhelm tests. I'm not sure what to make of that. I really wish we had an official Wilhelm report as the HPs and Epsons do; It would make an apples-to-apples comparison much easier.