The US still has a fairly robust network of VOR's / VOR with DME / VORTAC stations. Good for navigation, but there's no timing component, beyond what's inherent in how they operate.

Admittedly, that'll never be of use outside aviation as its line-of-sight only. But if the sun threw a Carrington event (or worse) at us, I think a lot of western aviation could carry on.

> The US still has a fairly robust network of VOR's / VOR with DME / VORTAC stations. Good for navigation, but there's no timing component, beyond what's inherent in how they operate. Admittedly, that'll never be of use outside aviation […]

I'm aware of the FAA's MON, Minimum Operating Network.

Exactly: that doesn't help boats. Or people in cars. Or farmers:

* https://www.deere.com/en/technology-products/precision-ag-te...

It doesn't help those that use GNSS for precise timing (TCXOes can only 'free run' for a finite amount of time before drift compounds 'too much').