* traceability of an application (or part of the application). For example, you send a message and don't see any reaction to it. Why? Was this message lost (sent nowhere)? Was it ignored by the receiver (or received by a different actor)? Was it received by the right receiver but handled incorrectly? It could be hard to find an answer, especially if there are millions of actors in your app.

* testability of your actors. Writing a unit-test for an actor can be a more complex task than testing some C++ function or class.

I think a good actor framework should provide tools for simplification of such tasks. And I can't image that those topics will sometime be covered by a C++ standard.

At best there will be in c++23 which means 2024 the time it trickles down to all relevant compilers and 2030 until you can use it in Debian stable.

That's also the time required by 32 successive 3-months javascript "zero to hero" bootcamps.