Honestly, if Apple releases an entire new look for UIKit without breaking retro-compatibility, I think the iOS team can be commended as one of the most impressive engineering teams in the world.
Why? Apps have already pretty well silo'd off their designs from the base looks and feel of iOS, and the ones that still rely heavily on it will probably be grandfathered in with the old look.
My guess is the core UI (home screen, title bar, alerts, notification center) will simply get a face lift, while individual apps will need to update to take advantage. I doubt we'll see a Metro style overhaul.
My guess is the core UI (home screen, title bar, alerts, notification center) will simply get a face lift, while individual apps will need to update to take advantage. I doubt we'll see a Metro style overhaul.