‘Growing a Language’ by Guy Steele is probably more relevant than ever here — and for all the dislike Java as a language gets, it is remarkable in how lean it remains even today, resisting the urge to add everything and the kitchen sink.
I have no idea how anyone could ever keep up with all this stuff. The language spec just grows ever larger each year. It's just far too much.
Imagine if all the authors of C++ compilers got together for an international symposium and some catastrophe struck. Like a gas leak causes an explosion and they all die tragically. I could absolutely see the language transitioning to being an anachronism. All the knowledge to actually work on the language implementation would be lost. We could still maintain existing software in C++ for a while, but eventually we'd even need to use legacy systems just to host the compilers.
Edit: downvoting will not change that