I've got ~230k on my original clutch master and slave, but the clutch itself was replaced at around 140k because I had the transmission out, not because it was worn out. The disk actually still had plenty of meat on it (lots of highway miles).

It might be good preventive maintenance to replace the slave cylinder while you're at it too. I've heard of lots of people saying the other failed soon after they replaced only one.

And its also a good idea to flush the clutch and brake fluid every 2 years or so to help keep all those components moisture-free and lasting a long, long time.