Parameters in SiriKit custom intents & Fine-grained Shortcut integration (apps provide blocks): Parameters are definitely in and I believe (from the SOTU demos) that the Shortcuts app can directly call into intents with parameters, thus enabling more fine-grained interactions. This is great news, and even if you don’t think Siri as a voice-assistant would be useful for your app, you should want this for Shortcuts integration.
On-device transfer learning in CoreML: This is also in and unlocks all kind of on-device ML applications. There is also a new category of “easy” ML integration (voice/sound analysis) along with a ton of other improvements. CreateML is now a Mac app instead of being integrated into Playgrounds.
HKLiveWorkoutBuilder (from watchOS) in iOS: I don’t see any mention of HealthKit or workouts at all in the release notes, so no luck here.
Web->AppStore->App ad attribution (w/o user tracking): Even though this was not announced, I have some hope that this could happen. The WebKit announcement of an privacy preserving ad click tracking mechanism is evidence that this problem is on their radar.
The App Store story is even worse, because there is no official way to pass some kind of data through your App Store URL that the App gets on first start. The normal attribution mechanism, IDFA, is not available to websites (only apps), so the only way to do a website-ad -> AppStore -> App attribution is for the web site and App to “fingerprint” the user somehow. One simple way is a correlation with time and an IP address, but that isn’t perfect. Unfortunately, many apps (and 3rd party ad trackers) do not stop there.
The last few years have been a cat-and-mouse game between Ad Tech firms finding loopholes in iOS (e.g. shared Pasteboards) and Apple closing them. It would be much better if Apple provided a privacy preserving mechanism and then explicitly forbade anything else in the developer agreement.
Multi-select image picker: No luck this year.