I still use my Loran C with joy. Other than those fickle changeover zones which you only hit every 600 miles or so for a brief unusable indication, I find my Northstar Loran to be as accurate as the GPS. As a matter of fact, the overlay of an NDB approach using all three finds the ADF to be the worst, the GPS to be second worse, and the LORAN C to be the best. Every time I switch it on I expect to get no signal acquisition, having been hearing about it being switched off for a decade now. I smile and love it when it's still up and running.
Have you ever wondered what would have happened on 9-11 if the weather had not been CAVU in both New York and DC? Maybe the terrorists had to wait until they were sure of VFR weather both places (and who knows what other places). Even had they been able to use GPS to navigate to downtown Manhattan, hitting those buildings would have been like threading a needle for an inexperienced jetliner pilot.
Perhaps an old non-WAAS GPS???
I have a Garmin 196 in my airplane, but the GPS systems we deal with in agriculture have <1meter precision with WAAS. We've had them for 3-4 years now.
We have one very high end system that uses "RTK", real time kinematic, to get < 1 inch precision using a local differential.
Taking down GPS would basically wipe out the modern surveying industry. I'd bet most of these guys would have to re-train on how to use the old equipment. If they still have it.