Earlier quoted context omitted.
Coin is like "Google Voice for Credit Card". Its a layer that sits on top of an old, crusty infrastructure that hopefully crumbles with time, but until then, we have to deal with it somehow.
Isn't the "old crusty infrastructure" in this case the credit card itself? It seems ridiculous to try to kill the credit card with... a credit card. I wouldn't be surprised if Clinkle, LoopPay, Square, or any of the many startups in this space kills the credit card (and thus Coin) before Coin makes its first delivery in Summer 2014.
I think Coin is a nice intermediate step between 10 cards in your wallet, and no wallet at all. Intermediate steps are viable businesses. I think Square is an intermediate step, and they seem to be doing just fine. They're obviously going to be at the forefront of eliminating cards all together, but they knew that credit cards aren't going away anytime soon, and so they leveraged that to get their foot in the door with the merchants.