Hardware ideas for iOS devices
1. One of my frustrations with the back camera is its location. It's very easy for my fingers to get in the way with it being so close to the corner. I would like the back camera to be dead center on the back of the phone. Would make the battery design challenging and they may to move to 2, but it's not like Apple haven't done 2, 3, 4 or 6 battery in one device before. Having it dead center would make using the camera easier to use imo.
2. There would be a magnets, alignment mechanisms, and power & data contacts around the back camera so that interchangeable lens accessories could be attached. The magnets and alignment mechanism would make easy plug and play, and the power & data contacts could power auto-focusing lenses and such.
3. Replace the home button with a micro-trackpad. So, take the best in class Mac trackpad, shrink it to round-rect of 20 x 10 mm or so. As with a trackpad on a MacBook, it would be mechanically clickable and would be operated with no functional difference from the existing iOS device home button. But since it is a capacitive trackpad too, additional functions can be perform with horizontal swipes, vertical swipes, single/multi capacitive taps. So, like the Palm Pre, various things can be done: horizontal swipes can switch apps and tabs, vertical swipes can bring up the app switcher, notification center, or Siri. Long presses, both mechanical and capacitive could be used too. I suppose you can have a setting to make the trackpad control input location in a text field.
4. Still want 4 speakers. One speaker at each corner for something closer to stereo in both portrait and landscape orientations. We watch more video on iPads, iPod touches, and iPhones than any other device in the house. By a whole lot.
5. Temperature and altimeter sensors. Along with GPS location & time, this would just add to the database of crowd sourcing data to look at what is going in maps and such. If properly calibrated, there could be a realtime database of worldwide temperatures overlaid in Apple maps. An altimeter is typically just a pressure sensor. So, it would also add to a world-wide database of weather data too, in addition to helping GPS determine altitude. It could also be added to EXIF or movie file meta-data.
Still lots of evolutionary stuff left on the table.