Hmm, some random musings:
Hardware:
As component prices fall, as they inevitably do in the computer world, there's always room for better specs.
- Increased working memory. 512MB? 1GB?
- Increased storage capacity. 64GB, 128GB, etc.
- Faster CPU.
- Faster GPU.
- More energy efficient components.
- Greater battery capacity.
- Lighter weight.
- More durable materials.
- Greater precision/resolution accelerometers/gyros.
- Camera... well, the thickness of the phone presents a physical limitation to what can be done with a camera. Packing more photoreceptors onto the same sized sensor doesn't necessarily equate to a better quality picture. But I'm sure people are working on that. However, I'd imagine there's plenty of room for improvement regarding the lenses, special coatings, etc. I wonder if they could fit optical image stabilization in there?
- 100% water proofing? That'd be cool IMO.
- Screen... It's already reached the resolution limit of human vision, so we're left with color gamut, contrast ratio, longevity, power consumption, viewing angle, brightness, etc. There's also e-paper and its usability of ambient light. We could see incremental improvement of specs, or even a revolutionary combination of LCD/LED and e-paper qualities in a single screen. (Personally, I hope Apple doesn't try increasing the size of the iPhone screen - that would require the device itself to be physically larger.)
- Given the physical limitations, I wonder what room for improvement there is with the speakers?
Software:
I'd like to see iOS gain more "general computing" features, like:
- A filesystem. (Including connecting to desktops and servers with shared drives.)
- Printing. (To avoid having to load printer drivers onto the iPhone, what about print to a shared printer on a desktop computer via Bonjour, which handles actually driving the printer.)
- Multi-user support. (Maybe. I'm not sure how often more than one person will want to use a single iPhone or iPad.)
But if Apple has determined that this would hurt their Mac sales more than it helps their iOS device sales, I could see it never coming to pass.
- Increased freedom to interoperate with other devices via wifi and bluetooth. (Including connection sharing.)