[WalterBright]

I've been cognizant of that for a long time. I figure if civilization collapsed, the human die-off would be something like 99%.

Just think of things like cars. It's fairly straightforward to keep cars pre-1980 on the road even if the manufacturer is no longer making parts for it. A craftsman can still make the parts.

But more modern cars? Fuggeddabootit. Watchagonna do with the computer systems? Write a few million lines of code? You can't even buy the chips anymore.