Specifically, P2137 spells out what key people (not only at Google) wanted and WG21 (the C++ Committee) said "No". Well I mean, as a whole, several of the P2137 authors are WG21 members, this was not a decision made with one unified voice.
Carbon has a few interesting ideas which I hope survive in at least some weird niche languages even if the Carbon experiment fails, because they deserve to be known to people who invent programming languages - some future Rust replacement might find a use for them for example.
But the most important thing Carbon got right that most of these C++ Successor languages did not, was that it understood why Rust is safe. Rust's safety is not primarily about the technology, although of course the technology is important, it's about the Culture, and Carbon understood that.
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p21...
Carbon has a few interesting ideas which I hope survive in at least some weird niche languages even if the Carbon experiment fails, because they deserve to be known to people who invent programming languages - some future Rust replacement might find a use for them for example.
But the most important thing Carbon got right that most of these C++ Successor languages did not, was that it understood why Rust is safe. Rust's safety is not primarily about the technology, although of course the technology is important, it's about the Culture, and Carbon understood that.