I'm neither too young nor too old and I think I won't be seeing a world war in my lifetime. Not even:
...when the US and Iran have a massive war...
I think if it will only be between Iran and the US, it will not be a full-blown war. Iran will be flexing all her muscles while the US will only lift a finger and we still know which side the tide will favor. This will just become another rape case in the Middle East, a total annihilation against a helpless opponent.
If a world war will erupt, everything will be cleared to the ground. It is certainly going to be a nuclear war. The world might be seeing a total reset and not even Bitcoin will survive. There is no point talking about the price of Bitcoin when the whole of Earth is turning into a Chernobyl.