There’s a pretty obvious thing about Objective-C 2.0, though: although the name was misleading, big changes like that were rare in Objective-C.
Releasing nit-picky breaking changes in Swift every year or two probably isn’t worth the aggro, but another option would be to gather together breakages in a once-every-five?-years breaking change. Not everyone’s favourite spelling change, but a curated list along the lines of Slava’s one for, say, Swift 10.