What about just shipping a fully automated fix-up tool when trivial but major breaking changes happen?
I'd definitely vote for a fix-up tool. I think it's fair on developers to make a change for consistency of the language whilst providing a mostly automated means to do a one-off fix. It'd be a small onus on a tiny subset of developers to sort out any extraordinary edge cases.
The alternative is to slowly build up a menagerie of quirks that put us on the same path as C++. I'm sure many of us would spend a bit of time writing a clever tool if it means we can rid ourselves of inconsistencies before they breed like rabbits. And it's better to make a change in the near term than to consider it in 5 years time.
