alt Hacker NewsC++ almost never removes features because of the ABI compatibility guarantees. Programs compiled with older versions of the standard can be linked against newer versions.
This is allegedly because in the 80s companies would write software, fire the programmers, and throw the source code away once it compiled.
Fixing syntax by definition does not affect the ABI. And Rust has shown that both ABI and API compatibility can be achieved in the presence of several "versions" (editions) of the language in the same build.