What is gonna happen once the post-apocalyptic scenarios come true?
Then not only Bitcoin, but all will be gone. All fiat money are fictional too, like the Bitcoin private keys without electricity.
Start collecting tangible goods - gold, silver, etc.
Learn surviving skills - archery, etc.
I agree with your idea mate. Worst possible scenarious are meteor impact and electromagnetic pulse attack where we don't know what will really happen but one thing is for sure economies and of course lives will be gone except for the precious stone and metals.