Alaskan
Almost Self-Reliant
ours isn't that, as you guessed, but another post-war quick and dirty material: asbestos cement. Since they are replacing the broken bits with a plastic pipe that fits inside, I was thinking the same thing about replacement. Though of course now it would snag at every repair - and there's loads of them!
The first house I owned .... down in Texas, had those WW2 pipes, we called them tar paper pipes.
Whatever... had to dig them all out and replace them.