https://9to5mac.com/2017/12/15/apple-watch-saves-life-managi...
Probably wouldn’t wear them all the time but when someone doesn’t “feel well”, a wearable in some form might save a life.
But shortly after it becomes optional, it will probably become mandatory (if previous safety technology is anything to judge by), and then you've got the government having access to live biometric monitoring data of every single driver on the road.