Interesting article, but it's really talking about ATM networks rather than the broader "banks". A bank's core systems could still hugely benefit from having an ACID compliant database even if any individual ATM node could still be allowed to operate independent for some amount of time to maximize availability.
Consistency is a feature whose importance is regularly downplayed by hawkers of NoSQL databases. I've seen firsthand what happens when a NoSQL database scales out and it's not pretty — a significant number of people end up spending a significant amount of their time trying to figure out how to maintain data integrity across failures in the system, even the kind of minor failures that are occurring every day. A lot of the time that involves going in and cleaning up data by hand. There is no general solution for this problem, and it'll be a persistent operational tax that dogs you as long as your NoSQL database stays in use.