I'm not sure what more you can expect from a phone. All of them are basically at their top. Yeah, they are faster and more powerful, but thats just so they can catch up with the apps, which are constantly demanding more. Not sure what else they could add to ''revolutionize'' a phone again. Only thing that hasn't moved forward as much as the other specs inside the phones is the battery.
There's plenty they can still do. Namely, add a lot more sensors. Not health sensors, as we won't be able to do many tricorder features for a while, and a heart rate sensor on a phone is 100% idiotic and a gimmick, as checking your heart rate at a given time is useless since anyone can do that by timing it with a clock. Health sensors need to be constantly monitoring, hence why Apple is making a watch (a wearable that is almost always attacked to your body).
The sensors I'm talking about are things like infrared, thermal, and 3D mapping sensors (among others). Virtual reality is going to be huge when the tech gets there. I imagine being able to hit the camera app (or a virtual reality app that uses the camera), to display live info on your screen for landmarks, street names, location names, on top of a slew of other things like object identification. Yes, this is a rare case but imagine you're in a smoke filled house which is on fire, you pull out your iPhone and you can clearly see on the display a 3D rendering of everything ahead of you, and where the fire is located based on thermal sensors. I really want to be able to hold my iPhone up and look at a tree and the iPhone to display the type of tree that is, live, on the screen, with information pertaining to that, or any other animate/inanimate objects. I also imagine the time where you'll be able to hold your iPhone up to a sign, or any writing which is in a foreign language, and it displays it perfectly in your native language, live, with absolutely no delay, like you hover over a foreign language and your iPhone display shows it in your language, but you looking at it in person, it is obviously a foreign language. Also things like showing you live on the display, your current distance from a particular point or object, your altitude difference, etc.
Another possibility in the future would be holographic projection, or at least normal projection, so you could watch a movie, view pictures, share a presentation, teach, etc. of course these would require new battery tech (please don't assume I mean current batteries could do this), on top of numerous other advancements I'm unaware of.
Anyway, just some futuristic ideas I have, which most are far off, so yeah I'm not sure they will change much soon.
