I was discussing this with a group of people today. We were wondering not only what more phones/iPads would be able to do in future but also about their design.
I'm not sure what more devices can do, although smart phones seem to be transforming into a form of payment system now.
Perhaps in years to come instead of doing the keys, phone, wallet grab as you run out the door you will only need the phone. It could be transformed into a house key in a similar thing way to how some hotels use swipe cards to acsess to rooms.
As for design maybe they will invent fold away ones.
What do you think or what would you like see?