Trading them is never going to be essential for survival. But mode of transactions from fiat to complete crypto is possible in far future. By that time most of the economic systems would have been made such that crypto would be regularly used by everyone. It would never be a drastic change but small changes over the years and not something to worry about right now.

Do not forget that in bare minimal survival, internet is not going to work, so crypto will not work either and fiat or lesser than fiat modes of transaction would gain priority NOT bitcoin.

For now just focus on accumulating more and more crypto.