I really doubt that such a large change can come before C++ lost all its momentum. (And you could even argue that that already has happened)

I’m currently stuck at work with C++14 as we need certain compiler qualifications (for safety in automotive). Even if that proposal would be in C++26 I could maybe use it in 2035 ($current_year - 2014 + 2026). In 2035 I doubt anyone in that domain will still write C++ as Rust is already making headway.

I don’t think it’s possible to make C++ safe without strictly limiting the user program to a subset of the language. There are guidelines for that (https://github.com/isocpp/CppCoreGuidelines) but even when I try to code in that style, I get to debug crashes the usual way. C++ makes some optimizations possible through e.g. move semantics that are absent from Rust and Ada but I wonder if it really matters these days. Rust seems to be displacing C++ for lots of new projects going forward.