Although it is a long-time off yet, we can now envisage a time when most of the developed world, and indeed most of the developing world will no longer deal in hard currency. There are a number of drivers for this:

1. Impact of mobile payments
2. Tighter money laundering requirements, and
3. Cost of physical handling versus electronic transactions

Since the mid-20th century many have heralded the impending cashless society, but it may be that the emergence of mobile payments is the final tipping point in that outcome. Indeed, empirical evidence is already available that cash is in serious, if not terminal decline.

Strong incentives
For years regulators and governments have worked to track the movement of physical currency across border, and in the case of terrorist financing and criminal activities. The Financial Action Task Force developed 40 core recommendations in 1990 (revised in 1996) designed to reduce the risk of money laundering, but the greater part of the effort was focused on the movement of hard currency and it's role in criminal undertakings. The reason for this is that it is harder to track currency, and if it can move freely around the system, the criminals, terrorists and "evil doers" can support their activities without restraint.

The strongest case for the removal of cash is around criminal activities. David Warwick posted an excellent review of the issues around cash and it's active involvement in crime in a recent post entitled "The Case Against Cash". In it he cites the following facts: 

"Now consider that low-level drug offenses comprise 80% of the rise in the federal prison population since 1985 (though those numbers have begun to go down in more recent years)...The vast majority of those illegal transactions are cash-based. Greenbacks are also the currency of choice for Mexican drug cartels, which funnel between $19 billion and $29 billion in profits out of the United States annually, according to the U.S. government."
David Warwick, CBS Interactive Business Network, Aug 2011

The biggest costs and risks are in cash
In recent times in places like the Netherlands, the cashless society has already started to become a reality. In 2010, the Amsterdam City Government moved to create 'cashless' zones in the De Pijp and Nieuw-West (New West) districts as a result of rising crime rates. You can now only use Chip and Pin to pay in those locations. This has been successful enough that it is now being rolled out across other districts in Amsterdam.

In Ireland, Belgium, Netherlands and other locations, banks are increasingly going cashless to reduce costs and crime. In recent years banks like SNS Bank in Utrecht and  National Irish Bank, were two such European banks to commence the move to Cashless. Both cited the rising costs and risks of dealing with physical cash, and low volume of real 'cash transactions' in-branch, as a metric for justifying the move.

Emerging economies may be first
In the Philippines, Kenya, Somaliland, Nigeria, Senegal, India and other such locations, the success of mobile payments and remittances is starting to see a dramatic shift in the day-to-day operation of the economy. In Somaliland where there are no ATMS, and almost no banking infrastructure, mobile payments enabled by mobile operators, the hawalad and money changers, might mean this province could become one of the first cashless societies.

The key to moving away from cash, is reducing the reliance on cash day-to-day. RBA Governor Malcom Edy noted that cash use in Australia had declined from 40% down to 30% of traditional 'retail' payments. In the UK, cash usage is also in decline, with the UK Payments Council estimating that it will represent just 0.8% of retail payments by 2018 (this is down from 90% in 1999). In both cases, the use of Debit Cards has been cited as the contributing factor.

It's all about behavioral shift in payments
The shift towards cashless requires reducing momentum in the 'cash system' by shifting to alternative modes of payment. The Debit Card has been an obvious 'cash-killer' in places like the UK and Australia, whereas mobile payments have had a much more rapid and profound effect on emerging economies. So with Peer-to-Peer (P2P) mobile and internet-based payments rapidly accelerating, and the move to NFC payments - the likelihood of 'saving' cash from terminal decline looks less and less likely. Check out PayPal's P2P solution using NFC enabled Android phones for example.

In this regard, the EU with it's strong support for debit cards, chip and PIN and increasing mobile enablement, and the emerging economies of Africa and Asia with both low friction against cash and the pressing need for financial inclusion, probably mean that the US, who is so strongly and emotively married to the 'greenback', paper checks and stuck with outmoded mag-stripe will likely be among the last to go largely cashless sometime in the next decade.

The momentum for these changes are building and it is a longer-term trend that will change the way we view banks and money in the very near future. The more friction you have, the more consumers will find workarounds. At the end of the day, a mobile or P2P payment will have far less friction than a cash payment.