Good points. I had recently been juggling the idea of what it would take to successfully replace cash and plastic with a mobile app, and rollout was a huge issue.<p>Depth of penetration is far more important than breadth. Ten thousand users in a single city is better than a million in a thousand. In order to be viable for point of sale, you have to give corner stores and drycleaners a reason to use your service, which means that their average customer has to want to use it. Sure, you can kickstart the process with big box retail chains, something that a company the size of Google is well-placed to do, but you'll never be dominant until you own the mom and pops. Without the ubiquity of credit cards, replacement mobile payments are at best a neat feature.<p>The author's second point ties into the first, and is equally valid. There is no discernible reason why Google would limit itself to a single credit card provider, unless that was their only option. All this will do is hurt uptake. The same is true of limiting it to a single phone.<p>Google needs to learn the Wave lesson, and go big or go home. By so meekly backing Wallet, they are all but ensuring its failure. This is no Android: it doesn't fix any big problem for any major player the way Android solved the OS and marketplace problem for the handset makers. Square works great for small businesses, especially those who provide on-site service. Wallet doesn't seem to provide any solutions beyond "paper and plastic are anachronistic". They really need to identify who their early adopters are going to be and launch a concerted effort to convert them. Short of that, it's another in a long line of half-assed product rollouts from Google.