Not the OP, but I do share the sentiment of improving existing unsafe languages.
The C and C++ code in many relevant stacks is not going away, and many of us won't be ever be able to use D or Rust regardless of how much we like them.
UNIX clones, Windows, .NET and Java runtime implementation, WinUI/WinRT, Android (regardless of this week's annoucement)
So Microsoft Checked C, Microsoft SAL, Visual C++/clang/gcc lifetime analysers, Frama-C, hardware memory tagging, Pluton sandbox, CHERI,... are all welcomed improvements.
Yes, I'm not against improving existing languages. I just don't think it's always sufficient, so we shouldn't accept the false dichotomy of improving existing languages or creating and promoting the use of new ones to take advantage of new ideas and technologies to their fullest.
Even if Rust were to fully supplant C and C++ for at least systems programming[1], we should hope that within a few decades it's a risk of being supplanted by something else. To want otherwise is likely to inadvertently want stagnation and/or a language that while likely still improving, is having new technologies and concepts bolted on in increasingly convoluted manner, as they were not and could not have been considered when designing the language originally.
1: I think this is unlikely, if only because I don't see one language supplanting C, I see C's market cannibalized by a few different languages, with C always retaining some use.
The C and C++ code in many relevant stacks is not going away, and many of us won't be ever be able to use D or Rust regardless of how much we like them.
UNIX clones, Windows, .NET and Java runtime implementation, WinUI/WinRT, Android (regardless of this week's annoucement)
So Microsoft Checked C, Microsoft SAL, Visual C++/clang/gcc lifetime analysers, Frama-C, hardware memory tagging, Pluton sandbox, CHERI,... are all welcomed improvements.