People would still be able to use any network for emergencies if their’s go down. If they only have one network in their area, they should have a landline or a sat phone if rural enough, since even a lightning strike could black their only tower out. It wouldn’t be too smart to setup an emergency plan on something with a single point of failure that could occur many different ways.

Though I’d hope a government or network provider points this out clear enough to anyone that somehow doesn’t get it.