There’s an important note. Verizon (and other American carriers) have no plans on shutting down 4G LTE. Even with c-band and DSS there are still large swaths of the country without any sort of 5G. In addition, devices a as recent as the iPhone 11 from 2019 do not support 5G.
The major American carriers are shutting down 3G. But for that to be a problem you’ve got to go back to the iPhone 5s, which has LTE data, but not for voice (going off the top of my head there, might be a generation off).
The major American carriers are shutting down 3G. But for that to be a problem you’ve got to go back to the iPhone 5s, which has LTE data, but not for voice (going off the top of my head there, might be a generation off).