These are collected from a Seattle-area Slack team I’m on. In no particular order, without any judgments about likelihood:
Side-loading of iOS apps.
Trials and upgrade pricing on the iOS and Mac App Stores.
The “plus” form factor is discontinued.
Run iOS apps on Macs.
Use UIKit to build Mac apps.
There is no OS X and iOS 10, only TEN.
iTunes is broken up into pieces, including a separate Apple Music streaming service app.
Third-party API for Siri.
The revival of the handwriting recognition API.
XPC services on iOS.
Two-up display from a single app on iOS.
Encouragement of MVVM-like architecture in UIKit and AppKit.
Keyboard-driven UI selection on iPad.
UIReact. (The person who suggested this is trying to get my goat, but I’m keeping my goat.)
5K Cinema Display.
NEW MAC PRO.
Drag-and-drop on iOS.
Lots more leather straps for the watch.
Apple Watch straps that add more functionality (GPS, cellular, etc.)
Apple Pay peer-to-peer payments. (SquareCash-like-thing.)
Apple Pay rewards cards.
Cram the whole computer in the Watch, and everything (monitor, keyboard, touchscreen) are all just wireless peripherals.
Major upgrade for HomeKit.
Rosetta for X86-64 on ARM (along with those ARM-based machines).
Siri-ous work on Siri.
Support for 32-bit apps to end on OS X.
OS X names: Barstow, Yermo, Shasta, Weed, Compton, Disney, Death Valley, La Jolla, So’side Quay, Tahoe, Truckee, Needles, Donner, La Brea, Stockton, Joshua Tree (for the U2 marketing), San Andreas.
FREE SONG ON YOUR MAC.
Siri on the Mac.
Core Data improvements. (Goes with San Andreas fault. Probably a small joke.)