I agree with the OP. I think the UI is a bit stale, but I don't expect any radical changes from Apple. That's just not their style.
However, the one thing that I personally would love and could potentially see Apple doing, is allowing the app icons to become a little more dynamic.
Similar to what they did with the "clock" app (by giving it moving hands), other app icons, both stock and third party, should be dynamic, and provide more info. The current static app icons are BORING and provide little value.
It would make the home screen come to life without radically changing the UI. For example, you can show the current weather on Weather app, recent photos on Photo app, currently playing album art on Music app, latest news on news app, GIFs of game footage on game apps, etc. etc. You get the idea.
The app icon would constantly be changing; at times the normal app icon, at others some other info or image that would have you fixated on your phone even more than before. Hahaha! [evil laugh]