This reads to me like an argument for better refactoring tools, not necessarily for looser type systems. Those tools could range from mass editing tools, IDEs changing signatures in definitions when changing the callers and vice versa, to compiler modes where the language rules are relaxed.
I was thinking about C++ and if you change your mind about whether some member function or parameter should be const, it can be quite the pain to manually refactor. And good refactoring tools can make this go away. Maybe they already have, I haven’t programmed C++ for several years.
