It will not work. If there is a need for fiat cash in the economy, they will start using euros or dollars instead of Swedish crowns (SEK). Injecting foreign ca

It will not work. If there is a need for fiat cash in the economy, they will start using euros or dollars instead of Swedish crowns (SEK). Injecting foreign cash back into the cashless SEK economy amounts to selling these foreign banknotes at any, available exchange point. They cannot reasonably ban these transactions, because foreigners bring these foreign bank notes along with them when they visit Sweden. If they insist on addressing that issue anyway, they will end up introducing Venezuela-style, self-defeating, absurdistan regulations that will make the situation only worse. They will be up against a growing number of people trading against them, in order to defeat such regulations, and to make money in the process of doing so. As always, it will be full of opportunities to thoroughly bleed them while making a killing. So, a Swedish economy without SEK bank notes is possible, but not necessarily one without cash. If that is the situation that materializes, they will have made the situation worse for them (foreign cash) instead of better (Swedish cash). You cannot outsmart economic fundamentals, because there will always be lots of money in punishing off such attempts.