SwiftTLS is non-blocking (using Dispatch). Yes, many libraries will have to be updated when async/await arrives, but I'd say that's business as usual for Swift developers (who have to do some refactoring every year anyway).

Also, SwiftTLS is not meant to be used in a production environment at this point. The disclaimer states: "It is not ready, has certainly a lot of bugs and received virtually no real world testing yet."