No matter how off the grid you think you are, you still depend on a massive support network of infrastructure.

Why does off grid power generation like this depend on support network of infrastructure?

BTC, like almost all currency, would probably be substituted for something, oh I don't know... actually valuable to survival?

Of course bartering will thrive, almost all currencies will become worthless, but what if there's one purely informational currency that's still remotely accessible? Again, I'm not saying there won't be disruption but the nature of bitcoin means it will find its way without internet and without electrical grids.