I don't see how cryptocurrency solves this - if you exchange your cash for a cryptocurrency then there are even fewer ways to spend it than when it was cash. I

I don't see how cryptocurrency solves this - if you exchange your cash for a cryptocurrency then there are even fewer ways to spend it than when it was cash. If you exchange your cash for (say) a Visa gift card or some similar reloadable card then you can use it wherever Visa works, which is many places (a lot of which would also accept cash) including online stores. And if the laws are changing to prevent cashless stores from existing then you can just keep your cash as cash.