Right, in future conflicts between major countries the satellites will be first casualties. The US military is aware of this and still trains personnel on analog navigation techniques. Inertial navigation works well for some missions and research is underway on alternative technologies. Civil airliners can still navigate without GPS, although this may reduce safety and increase workload.

https://interestingengineering.com/military/us-military-nail...

We're also going to need a prompt launch capability to replace attrition losses. There should be warehouses full of spare navigation, reconnaissance, and communications satellites ready to mount on a reusable booster and launch within hours. Concerns have been raised over a "Kessler syndrome" due to orbital debris but in lower orbits with significant atmospheric drag this won't be a serious problem.

Reminds me of in the Avengers - SHIELD couldn't navigate the helicarrier, and Nick Fury said "Is the sun setting? Then put it on our left!"

IIRC, the Navy stopped teaching officers traditional ship navigation methods for awhile, until the series of incredibly stupid incidents drew attention to the lack of basic navigation and piloting skills, then curriculums were partly reverted. Not sure if things have improved much; probably too early to tell.

I doubt officers or crew would ever have to resort to a sextant, but that's besides the point. It's the type of thing that's integral to learning navigation theory and building tacit knowledge that's fundamental to the job.

EDIT: 2016 article discussing restoration of traditional navigation instruction: https://www.npr.org/2016/02/22/467210492/u-s-navy-brings-bac...

The truth was the first casualty.