This isn't quite accurate; Mojo uses the same memory safety approach as Rust. It has some mutable aliasing, but only intra-function, so in practice programs will be pretty much Rust-shaped.
My hot take is that what a good C++ will act like is basically just already Rust, mostly because the main problems with C++ can only be solved by taking away some of what makes it C++ in the first place. Some C++ developers will probably not be happy with a language that takes away the parts they still want to use, but others might just not like what Rust "looks like", so if dressing up the same Rust semantics in a new skin ends up getting the world more code written without the bad parts of C++, that's probably a good thing.