I think eventually the mobile data radio is going to migrate out of these mini-tablet interfaces we call phones, and into either a wrist-watch or pocket-watch form factor, with local wireless accessories fleshing out the rest of the UX.
Rumours earlier this year said that they dropped plans to add a cellular radio into this year's watch due to battery concerns. Give it another year or two and they may solve it.
Then you could leave the house with nothing but a watch and wireless headphones and do various tasks from working out, listening to music, calling and messaging people, getting directions or booking an uber. No phone required.
