It's unlikely that they'd just kill sheets, even if they adopted new primitives.
You can still use storyboards in Swift iOS apps despite them shifting away from them being the focus with SwiftUI.
React Native obviously avoided it, but the biggest paradigm shift by far was the switch from Objective-C to Swift as the core language for Apple devs
(But Swift is a way better language, it was so worth it)
over 1 billion people on planet earth are iphone users, a UI design overhaul of this magnitude will 100% have a cultural/psychological impact and shift on the human species
we tend to overlook the sociological/anthropological/spiritual impacts of tech changes like this
There is always the rush of early adopters (🙋♂️) and the inevitable push back from people who don’t like change, and that goes on for months and then everyone gets bored after the benefits float to the surface and we have harmony for another 10 years. Kinda.
I doubt the layout of apps is going to change all that much, just the styling.
In my case, I'm banking on SwiftUI code just looking mostly right in the new UI paradigm from the get go. Might have egg on my face in a few hours, though, we'll see.