Tarnishing has nothing to do with the fact that the hardware is or isn't coated.With the hardware, you can have all the coated brass hardware replaced (D rings, square rings, bolts, zip pullers) at a cost but as they are coated, it will tarnish eventually. This does not mean they will replace the zipper, top handles and straps with new ones though. As my main concern was the canvas itself which can't be repaired, there was no point in getting all brass hardware replaced.
Hopefully my Speedy B will continue to hold up for many more years to come. I love this bag so much that when it gives up on me, I might actually consider getting the same bag in the future. : D