Well, a cemented rock wall would be more durable, but also a lot more money and a lot more work.
The life of this fence I would guess will be between 30 and 50 years.
It will be interesting to see if anything knocks it down, as is wont to happen from time to time.
Yeah, that was what I was thinking for a lifespan. I was shooting for over 20 years. Considering planting Osage Orange along it in some years and letting a living fence swallow it up near the end of its lifespan to replace it.
I was worried that the rock would need a binder/cement to help it to stand the test of time. But I think your ides of a living fence is a great one too.