I'm thinking along the lines of a wearable device (or some other configuration where it's not intrusive-- I think the intrusiveness is the only problem left to

I'm thinking along the lines of a wearable device (or some other configuration where it's not intrusive-- I think the intrusiveness is the only problem left to solve). Much like the phone (particularly the iPhone) absorbed the function of calculators, watches, and note pads (and to some extent cameras), I think this trend will continue. Now, I'll admit, the extent to which the phone solves this problem may only be so great for people who are now early teenagers (hell, I still wear a watch...), but I suspect it's coming.