I've pondered this question for some time now (like many) and always come back to the view that the watch is a really, really nice add-on to the phone in my pocket, but not absolutely essential. I'm starting to shift, however, since using ApplePay on the watch more and more. Perhaps not right now, but maybe in a few years, when mission-critical functionality resides primarily on our electronic devices, it's going to be rather nice to have a backup device on your person should the other device fail. By mission critical, I mean things like: credit cards, boarding passes, public transport passes, car unlocking and starting, home security systems, hotel room keys. Things which absolutely must work 100% So, could having two devices, on your person, start to be seen as a huge advantage? Could something as simple as, "redundant backup" be Apple's killer app? Thoughts?