> In that sense, I think Rust has a real shot at at least severely wounding C++ or at least opening the door for the real C++ killer (it might be that Rust is a smidgen too strict in the mut ref department to really kill C++, I'm encountering a lot of push back from experienced C++ devs).

Experienced X devs pushing back against Y doesn't mean that Y isn't going to displace X; the big factor in displacement isn't whether experienced devs will voluntarily shift (even if Y does displace X, the experienced X devs have the most vested interest, and will be among the last to voluntarily move to Y.)