Swift apps no longer include dynamically linked libraries for the Swift standard library and Swift SDK overlays in build variants for devices running iOS 12.2, watchOS 5.2, and tvOS 12.2.
Quoted from XCode 10.2 release notes
You do not need to migrate Swift 4 code to Swift 5 mode in order to use Swift 5’s stable ABI,
Apps using bundled runtimes will however not get the benefits of App Store app thinning.
Quoted from Swift.org
What should I conclude from above?
Apps built using XCode 10.2, Swift version 4.2 will still bundle Swift runtime libs to support < iOS 12.2, so even on iOS 12.2, we won't benefit from App thinning (use Swift runtime libs from iOS and strip bundled one)?