One company, Bionym, is already doing something like this. Their Nymi wristband is an ultra-secure means of personal identification. Put it on and touch it for four seconds, and it takes an EKG with a fidelity comparable to what you would get in a hospital. It is then matched with a previous distillation of your heartbeat pattern stored in the cloud. Once you put on a Nymi, until you take it off, it uniquely identifies you. Current applications include unlocking your laptop or smartphone, but Bionym CEO Karl Martin tells me his company is also working on a version that can be used for contactless payments, just like many smartphones (including the iPhone 6) and the Apple Watch.

During Apple’s presentation, Apple Vice President Kevin Lynch announced that BMW has developed an app for the Apple Watch that will allow users to lock and unlock their BMW i-series electric vehicles. And Mr. Martin told me that new bluetooth-enabled locks from companies like Lockitron and Kwikset mean that the moment you walk up to a door while sporting a recognized wearable, it can unlock without a touch.

Put all these possibilities together and what you get are a suite of functions that could almost, but not quite, be conveniently accomplished by a smartphone. Just as Uber could in theory work on a PC but didn’t really make sense until the dawn of the smartphone, body-wide wireless networks and computers we never take off will create applications that simply don’t exist yet. Wearables won’t just appeal to fitness nuts and quantified-self geeks. They will appeal to everyone, because they will be the primary, perhaps even the sole way we identify ourselves to a world full of smart objects.