<i>Physical</i> currency is going away in our lifetimes. What it is replaced by (digital cash owned by governments, corporate scrip, independent decentralised currencies) is up for debate, but its demise is not.<p>Physical currency is controlled by governments, since it is expensive to produce and distribute, and network-connected payments are becoming more and more prevalent, it is inevitable that at some point the cost benefit ratio becomes untenable for governments and they remove this option.<p>If you fight for its existence against the government which claims sole jurisdiction over it in the first place, you're fighting yesterday's war, and doomed to lose, better instead to imagine a different future based on digital currencies (of whatever stripe). I'm not keen on bitcoin et al, but the future is clearly not in physical tokens which represent fixed denominations of currency.<p>If you were starting a currency today, would you start with cash?