If you're in the west, I think you'll be okay, you always have WiFi and breaking the internet is not a bitcoin specifically targeted attack, many people won't be able to use things. Maybe even card machines will stop working too.

Always good to think adversarially and consider what your use case and threat scenario is so you can think of solutions, just don't get stuck in a loop thinking too abstractly. Think about real use cases you can imagine yourself in and consider how likely it is before getting yourself too concerned.