[leoc]

The iPhone's still a heavy, bulky, expensive and fragile thing to take with you to the gym or out running, as are other smartphones. The screen is also not easy to interact with while you're exercising seriously. However, smartwatches or smartglasses with 5s-level-or-better motion sensing and the capacity to run apps independently of a smartphone do have to the potential to make dedicated fitness trackers mostly obsolete, though expense and fragility will still be concerns.

EDIT: This Gruber reaction http://www.cnet.com/news/nike-fires-fuelband-engineers-will-... heightens my suspicion that this is an early omen of an Apple smartwatch launch.