Google started work on Carbon due to the difficulty of getting the C++ standards committee to accept any real, fundamental changes to the language. If Google, a grandmaster at manipulating standards committees, couldn’t get something passed, I don’t foresee this proposal getting anywhere.
It boggles the mind that any language - let alone a systems programming language that most of the world’s infrastructure is built upon - wouldn’t adjust their specification to eliminate undefined behavior wherever possible. And C++'s all seem to be in the worst possible places, too.