Re: Oh yeah, and by the way...
They used to be 2,500 , but as you said above this makes all kinds of things possible, Military comms when you enter buildings tend to unsynch/lose trust and take ages to reestablish, not with this. Drones, signal jammers etc all do or can use accurate time.
Automated grain carts and plows can keep a GPS fix and work when it drops and they have fixed points to locally improve the GPS signal this tech benefits from. Not right now but if it's cheap enough.
GPS only came about (sort of) through tests requiring accurate clocks in space and realising you could work out the position of the satellite through the doppler effect like with Sputnik. Reversing that and with a load of extra ones you can navigate on earth.
I like to see anything that makes this kind of tech cheaper, there are most likely big important future things that will need this kind of accuracy probably autonomous vehicles but maybe