Another railraod in a similar situation may be the California Western (Skunk). They haven't hauled freight in decades (since the Fort Bragg mill went away as well as NWP service). But I think they're still technically a common carrier. And the NWP technically isn't abandoned - it's out of service for at least a couple of decades, and probably will never come back, but a similar conversation to Big Trees may occur when the time comes to actually pull the plug.

OTOH, what about truly isolated operations like Black Hills?