Just in case you were wondering how this would work for the un(der)banked.
PayPal has been extending its reach to POS:
PayPal and Discover made a deal as well: http://www.forbes.com/sites/chrisbarth/2012/08/22/discover-and-paypal-join-forces-in-the-war-against-paper-money-banks/
I was talking to my sister about garage sales, because while obviously people who have moved to selling online whether through eBay or other, are going to have the ability to take payment cards, PayPal, etc., and presumably anyone using Craigslist has the capacity to figure out how to make PayPal or some similar payments system online work for them, only people who do really frequent garage sales are going to set up Square, say, and a lot of the people going to garage sales aren't necessarily going to have a smartphone with them to use an online payment mechanism.
But then she pointed out that at least around where she is, she's not seeing hardly any garage sales anymore, and I realized that the only ones I seemed to see anymore were sort of the running-a-junk-shop-in-the-front-yard type of thing. I'll have to keep an eye out for signs for a while, but maybe garage sales were long ago done in by eBay, Craigslist, freecycle [eta: , consignment stores], and so forth, and I just failed to notice.
Okay, but this is more relevant to the question. They have not gone away.
ETA: R. sent me this:
If Dick's starts taking cash, well, wow. I feel bad for the ATM guys, in a way. This could be that last bloom of hyperactive life before extinction.
Then again, maybe not. Seattle has been an early adopter of all kinds of things vs. most of the rest of the country. Seattle could get rid of cash (what would you give the Real Change guys instead of a $1?), but that doesn't mean the rest of the country will.
This article does illustrate a typical flaw of payment system coverage, in that one system (cash) is treated as no-cost, and an alternative systems costs are mentioned negatively. Cash _is not_ free. "The government" (which, let's face it, we do all pay for, one way or the other) and the banking system, merchants and so forth are paying costs associated with cash. Really.
(A grand don't come for free. I sure love The Streets.)