Actually, the question was, "....what would really happen if there was a really big disaster that kills your cell phone coverage and your satellite or internet, so gee what would be left still working?"
Your answer was that it's Homeland Security's responsibility. I'm glad you added "for better or worse", because, by and large, the DHS's performance leaves a lot to be desired.
While that is an answer, it isn't the answer. While the power to order a facility to shut down and evacuate might lie entirely within the realm of the local emergency officals' domain, depending on the area, local emergency officials will work with the local broadcasters and can suggest that they shut down and evacuate but leave the actual decision to the manager of the facility. They have this relationship because of their ability to broadcast. So, a more complete answer to the question is that radio could/would be still working...whether or not the DHS chose to use them..afterthought or otherwise. Of course, whenever they decided to show up, if they didn't use radio, I suppose we're back to the 600 cans and a long piece of string scenario.
And regardless of where the "responsibility" for anything resides, "initiative" and "drive" and "motivation to succeed/excel/survive" have been qualities that promote forward movement/progress/survival. Blindly relying on someone or some entity to merely fulfill their responsibility in times of crisis, blissfully ignorant of the consequences if they don't fulfill them, courts stagnation at best, a far deeper crisis at worst.
I respect a lot of your views, Big A, but I get the feeling that you are more comfortable coloring within the lines while some of us occasionally color outside of them. It works for me. I cannot speak for others.