Effectively a perfectly interopable (both ways) subset of C++ with some syntactic sugar and niceities.
But yes I agree that best practices of modern C++ means most of the baggage and bad ways of doing things don't have to be done. Now just to enforce it via education and linters or something conventionally.
So I don't really see why Carbon is at all interesting other than it just being another form of their standard "Google being Google" with their extreme "Not Invented Here"-itis. It just sounds like a slightly warmed over version of C++ with different syntax and near identical semantics.
Carbon at first blush appears to show that Google doesn't appear to understand the real problems with C++.
I can't see why anyone other than Google would ever end up using the language, at least as currently described by Google in their goals for the language. In general for something to be rewritten it needs to cause very substantial advantages to justify the rewrite.
If you are in a position where you can wholesale rewrite your program (or are starting greenfield), Carbon is pretty clear upfront that you should use another language: "Existing modern languages already provide an excellent developer experience: Go, Swift, Kotlin, Rust, and many more. Developers that can use one of these existing languages should."
Natively fitting into the C++ ecosystem at Google and in some other extremely large C++ codebases (e.g. being able to directly use templated C++ code, using the same build system, bidirectional interoperability) is what is being prioritized.