The iPhone form factor is here to stay: it’s about the largest possible device that still fits into a pocket, and unless we all change our dressing habits in 10 years (unlikely), we’ll carry a device with that form factor.
It will be improved, of course, with more memory, more sensors, more connectivity options, more situational awareness, more data feeds, better screen resolution and so forth, but it will be very recognizable with what we know now.
It will still make and receive calls, and we’ll still use it to look up information such as a map of our surroundings.
It will also become the hub in a hub-and-spoke system of communications with smaller devices we’ll also carry. Today’s Bluetooth headphones are the first example of that. More in a separate post.