I think that if you change the C API officially to introduce one feature you'll realize it's a significant milestone, so you'll end up trying to fix everything

I think that if you change the C API officially to introduce one feature you'll realize it's a significant milestone, so you'll end up trying to fix everything else, too, before it's once again locked in stone. I'm sure a lot of these languages started that way and fell down the same rabbit hole. But that's not necessarily a bad thing. Whether you create a new language or update the old, it's still a step forward.