The thing is that GPS doesn't just do positioning. If we lost GPS then we can just look at road signs (hopefully). GPS also provides time synchronization to a lot of very important telecom infrastructure. To prevent 4G base stations and digital TV transmitters from interfering with each other, their transmit reference clock frequency need to be disciplined to within 50 ppb and their time need to be synchronized to less then 1 us.

No GPS means no 4G and no digital TV. And technology leapfrog effect means that third world countries will be significantly affected, as they jumped directly to mobile phone: https://www.cio.com/article/194000/what-does-technology-leap... . And countries are moving toward digital TV from analog TV: https://en.wikipedia.org/wiki/Digital_television_transition because they want to free up the spectrum for cellular network.

This is bad. The transmitter towers aren't moving anywhere soon, so the obvious solution is to move them to fiber timing network. Wired is always more reliable then wireless anyway, ask Linus Tech Tips. Only China understands this though: https://www.gpsworld.com/china-finishing-high-precision-grou... and https://cpl.iphy.ac.cn/article/10.1088/0256-307X/41/6/064202 . EU is moving toward that: https://www.gpsworld.com/europe-moving-toward-a-timing-backb... . US is hopeless