For what it's worth in case anyone from Apple is reading ;-)
My wishlist for iOS 10.3, or any future release for that matter:
Overall
- Customisable control center, like notification center
- Force Touch control center for e.g. Wifi, Bluetooth,
- Customisable default apps for Mail, Calendar, Contacts, ...
- Widgets on lock screen (so I can see my Runkeeper progress without unlocking, use my iPhone in nightstand mode like the Watch, or use my old iPhones as wall-mounted HomeKit controls, ...)
- Multiple users on iPad
- Allow iPad to access files shared from macOS
- Multi-tasking multiple instances of same app (Safari split screen is a hack, why is this not available for all apps??)
- Add apps which are missing on iPad (Weather, Calculator, Voice Memos, Phone)
User Interface
- Dark mode
- Merge long press & 3D touch
- Introduce an "edit" sheet separate from the "share" sheet (it is so confusing to find certain functions hidden under "share")
Home Screen
- Live icons - Apple's own icons (Calendar, Clock, Weather) have been allowed some type of interactivity since iOS 1, why hasn't some API for this been made public?
- Smarter method for rearranging icons (e.g. move multiple icons at once, or auto-sort most used to 1st screen)
Siri
- On-device Siri
- Textual input for Siri (i.e. merge Siri with Spotlight - why are there 2 separate search interfaces?)
Settings
- Reshuffle the settings menu.
- Make "Accessibility" a top-level item (so many cool things in there)
- Allow access to settings both from within the app and from within the Settings screen. It's confusing now that many apps require some settings to be handled via "settings" and some via "options" inside the app.
- Specific example of this - why can't I edit the Notifications screen from within the "Notifications" page of the Settings app? Why do I need to scroll down on notifications and press edit?
Music
- Make it more usable for people who only use their local downloaded library, no Apple Music
- Merge the iTunes Store app into the seperate apps for Music, iBooks, Videos, Podcasts, ...
Photos
- Sync faces across devices!
- Better user interface for face detection adjustments: why on earth is "not this person" under the "share" sheet? A multi-picture "click all pictures of person X" view would work much much faster than the single-picture "is this X? Yes / No" screen that they have now
- Allow albums from the "Albums" tab to also be shared under the "Shared" tab rather than requiring 2 completely seperate albums for private collection vs. sharing
- Better user interface for the markup options (hiding this behind the "more" button sucks)
Health
- Sync from iPhone to iPad. I know they wouldn't want to sync over iCloud due to privacy concerns, but I would imagine some type of local sync from iPhone to iPad should be possible, just like how the Watch syncs to iPhone
- Allow entry of non-quantitive info, like listing when I sprained my ankle, had a cold, got a flu vaccine, ...
- Allow me to enter info for my kids as well. Fevers, childhood diseases, growth, how much milk the baby drank, ...