It uses slip rings like your alternator, not a commutator like a typical brushed DC motor. I’ve had alternators that have lasted more than 20 years, and they don’t have dust problems. There’s no arcing and there is a continuous contact surface, so there isn’t really any dust.
But what about the dust accumulating inside and sticking everywhere, adding additional wear.
I guess we'll see how many iXs are still on the road in 5 years.