It can happen if all the countries together shut down bitcoin if they felt that it is less profit and harm to the environment because the heat generated during mining and the electricity spent is more and the future of bitcoin is still being talked about But no one knows when what will happen
i slightly disagree with what you say.
you say if all countries shut down bitcoin simultaneously, it's very unlikely. because some countries have recognized that bitcoin is an investment asset for the future and not as a transaction tool.
and if all countries shut down bitcoin access, that's also very unlikely. because everyone will still be able to access bitcoin by all means to get access to bitcoin. considering bitcoin has no laws a country cannot prohibit.
like in my country, it has recognized that bitcoin is an investment asset and has asked for an asset tax from crypto.
so from this we can conclude that bitcoin can never be $0. unless the bitcoin owner closes the network