We have seen in SE-0241 that having a stable ABI will commit Swift to good and bad designs. I don't know much about what ABI stability means but from the (mis?)understanding I have, I have concerns I'd like some perspective from the community on.
My worry centres around this: I don't want to wait years to take advantage of new Swift features or bug fixes. For example, if first class language support for concurrency comes in Swift 6, I don't want to have to wait years until the Swift 6 ABI has been distributed to enough of our user's install base.
Can we still bundle Swift with our apps so we can choose to use the system provided Swift or not?
If there is no choice, could (for example) the App Store app on iOS 13 download newer versions of Swift for the system when it's downloading an app built against the corresponding Swift version?
If there would be a delay waiting for Swift versions to be distributed to users, it would obviously have a negative effect on the development of Swift since there would be less opportunity to learn how people use these features.