Blackout
"I really shudder to think what the consequences would be of a prolonged power outage once we've moved to an all digital telephone system."
Well, we'll never know because you won't be able to communicate with us ;-)
If you are reallly that isolated, I recommend a sat phone - they aren't too expensive now.
Assuming of course that WW3 isn't the reason why the rest is offline, in which case you'll have nobody left to phone even if the satellite is still in the sky