Happy WWDC day! No predictions, but one thing per platform that would make my life better:
iOS: APIs for launcher/clipboard apps like Alfred/Raycast/Quickbar
iPadOS: multi-user support
macOS: calendar sets in Calendar
visionOS: Microsoft Authenticator support
watchOS: New Siri watchface based on widget system
tvOS: Netflix support in the Up Next Queue
HomePod: Siri parity with other platforms
HomeKit: Matter 1.3 adoption