Correct. When I did the presentation, I did mention we attempted to type Elixir and failed. Therefore, the idea of saying the language was "complete" was precisely to signal the community that most of the work would happen in the ecosystem and not by directly changing the language. Especially because:

* The language was designed to extensible - see how Numerical Elixir can compile Elixir to the GPU and it didn't require changes to the language (we improved the language based on some needs but it was never a blocker)

* A lot of the hard work that makes Elixir better every year is actually happening on the Erlang VM, which we mostly get to leverage by doing nothing (for example, Elixir "got" a JIT since I said we were complete and we had to change nothing)

I'd say the definition of "completed" still holds, because we haven't announced changes to the language yet, but if the work on the type system succeeds, then we will introduce a new typing annotation, which is definitely big enough to void the label after 7-8 years.

Strictly optional and without changing the language API, fwiw. So about as smooth/painless an experience as possible.

Its addition into the next minor verision (1.17) will bring warnings that address some of the most common footguns in the language, like comparing structs.