This is one of the predictions I would include in my list for key trends over the span of this decade (rather than year). I might in weaker moments also conjunction fallacy it as an Apple product. I think there are some prereqs that still need to be addressed at this point including further maturation of mobile apps, some addressing of social acceptance of life tracking-style media recording, battery life, etc. So yeah.. S curve cumulative probability hitting 50% around 2020 that these achieve iPod like sales figures.

75% probability of being mainstream, or at least not unusual, by 2020. It seems like the obvious solution: phone screens are too small, laptops and even tablets are too inconvenient to carry around constantly. And I'd go 50/30/20 on the first mass market product being based on Android/Apple/other. (With Android, anybody can build it without asking for permission).