After more than a year of using personal behavioral trackers, I have developed a few unscientific, armchair theories.
Theory 1. The personal trackers, as we know them, are not going to scale in a global way. The main reason is that obsessively keeping tabs on ones habits is simply not a normal human condition. Wearables generally may have a longer life, but they will be dramatically different from what we see right now. There might be a case for very stratified, diagnosis-specific hardware (we already have holters, pacemakers, blood sugar measurers, and there might be others such as the insulin-sensing contact lens), but personal behavioral trackers will either die away, reimagined, or remain confined to small geographic bubbles such as San Francisco and Brooklyn, or interest-based bubbles such as runners, health-geeks, those wanting to lose weight, and the like.
Theory 2. the only hardware that humans want to actually carry is a phone, and that is not because of the phone itself but because of the inherent human need to communicate. Growing up, my family in India was the one of the rare ones with a phone, and we were the communication hub of the neighborhood. As phones slowly become more available, there would be long lines at public phone booths to make a long distance call—everyone wanted to talk with their loved ones. I was living in a real-life experiment.
Perhaps a phone-based tracker might have more life, and this is where Apple will likely show the way. The problem with even a phone-based tracker is its short battery life that is made even shorter if you incorporate GPS, and without location most info is boring. It is a difficult problem which is why Apple hasn't announced anything.
Now, to be clear, the importance of individual info is not going to diminish. But in order to realize full potential from it, we will have to drastically rethink our notions of privacy and security.
Open hardware and data certification are intrinsic parts of this ecosystem of sensors. Open hardware both consumes and spits out information, hopefully all open, and allows a grounds-up action to take place harnessing the global innovation potential without being dependent on what catches the fancy of Silicon Valley entrepreneurs. The world is very big, and to make a change that affects billions, we have to think really outside these polygons.