One of the things you may’ve missed from Apple’s announcement(s) is the fact that new iPhones also come with new motion co-processor.
The earlier rumored “Phosphorus” chip is now officially known as M8, as opposed to M7 found in the iPhone 5S.
What makes the M8 better than its predecessor is built-in barometer, which will enable improved tracking of one’s motion, steps and so on.
Presuming user gives its consent, Apple will collect of his/her activities in the HealthKit platform and provide access to this data through the Health app.
Said platform and application were announced during this year’s WWDC and are set to debut with iOS 8, and new iPhone 6 and iPhone 6 Plus.
It won’t be Apple’s data only; HealthKit will be open to third-party developers as well which will be able to use this information to build new apps and services. However, they won’t be able to collect that information and sell it to third parties due to Apple’s recent policy change.
It remains to be seen whether this new chip can make some basic fitness trackers obsolete. I would say that this category will still find its audience but with the rise of smart watches, their appeal will fade away.