Anyone who spends time and treasure preparing for painfully sustained emergencies reveals at least some pessimism about the manner in which we have organized our world. You have enough concern about existing means of communication to at least think about it. Good for you! There is ample evidence that we've built a world with far too much tech to maintain without inevitable failures.
The aging power grid in the US will quickly become a major problem in any SHTF scenario that can be conjured. The cost to replace it is enormous and I'm not even certain with $34 trillion of debt the US could afford to revamp the entire power grid system even if it really, really wanted to.
James Howard Kuntlser once wrote about this:
Imagine: Bitcoin shoots up to a million dollars. You're a zillionaire! Uh Oh. . . somewhere outside Zanseville, Ohio, a squirrel takes a final chaw through some old insulation on a wire coming out of a transformer. His head blows up in a blue arc flash, and in a few seconds all the electricity goes out from Chicago to Boston. It turns out that seventeen substations in ten states have blown relays, transformers, and switchgear. Some of those components were forty years old and are now manufactured twelve thousand miles away in a country that doesn't like us anymore. The replacement parts get held up in a Chinese port. The power doesn't come back on for weeks. Nobody who lives in the eastern USA can get to his Bitcoin wallet, which is just a virtual entity made of computer code residing in a digital cloud, i.e., nowhere real...
Even if the grid doesn't technically fail, control of it may fall into the hands of jack-booted thugs who could benefit from pulling the plug on select regions. However that turns out, assuming that power will always be available is a terrible assumption. And the lack of basic power impacts everything...
In 2005 Central Indiana experienced a once in a lifetime ice storm. Power lines were down everywhere and power wouldn't be restored at my house for eight long, agonizing days. But that was the least of our problems during the first 72 hours. With power off the internet was down. Gas stations had fuel and kerosene in their tanks but without electricity, no way to pump it out of the ground. Portable generators got those pumps running by the 3rd day of the crisis, but with no internet connectivity anywhere in town gas stations and other retail outlets (grocery stores) couldn't take a credit card. And since power was down on a broad scale, ATM's were out of service. You got a suitcase full of cash at home and you might do okay, you got ten bucks in your pocket, and you were effectively "broke".
I'm an engineer, I know how a lot of things work. But that ice storm experience gave me a different perspective about the way things work and believe me, we've built most things wrong. I mean, unless you believe in magic, miracles, and a lot of good luck, then just over the hilltop lies an ominous future.
Access to power is the number one concern for surviving the zombie apocalypse. You may disagree, but power generation needs to be very high on your list. Remember, if the power and internet are out broadly, no one will be able to let QRZ know you've become a Silent Key. Best you solve the power problem first, long before worrying about stockpiling ammo and MRE's.
Believe it or not, we're only one ex reality TV show asshat from total disaster. The end of the American experiment could go something like this...