I'll silence the crickets ...
To answer your original question, 418,000km is possible. My clutch is fine, just like new. But I am "super" easy on the clutch, plus the original owner. And I've put on 99% of the km's, so I know the clutch's history. I'm sure it will easily last to 500,000km. Maybe 600,000km if I keep it that long.
I agree with Silentnoise713 in that it really depends on how you drive the vehicle.