There's a huge amount of legacy code that cannot be replaced overnight. There's thousands of person-hours invested in such codebases and they need to be maintained. There's also a much greater number of experienced C++ programmers available versus Rust programmers with the same level of experience (especially working experience, not just the language itself), so that's another factor.

So companies with lots of earning potential in greenfield projects might indeed have a competitive advantage, while it's more difficult for those with products that have a large existing C++ codebase.