José is quite prolific, so I think it's natural that he moves on to things like this. It's hard to know what reception will be like until you build it.
I think often this happens more or less by accident rather than conscious design - but think of something like PHP which made it really easy to whip up quick web pages, or Rails which drive Ruby adoption for a better, more structured, but still dynamic and quick web programming experience.
And I suppose part of those happy accidents are people just hacking on something they think is cool, so I wouldn't stress too much about the "marketing aspect". I'm just curious what drove it.
This particular effort started because some people got together and realized that we could do it! Do it in a way that felt part of Elixir and not just a bunch of bindings to C libraries.
We honestly never had the expectation that we had to beat Python (otherwise we would simply not have started). Early on, we were not even sure if we could be better at one single thing. However, 3 years later, we do have features that would be quite hard or impossible to implement in Python. For example:
* Nx Serving - https://hexdocs.pm/nx/Nx.Serving.html - allows you to serve machine learning models, across nodes and GPUs, with concurrency, batching, and partitioning, and it has zero dependencies
* Livebook - https://livebook.dev - brings truly reproducible workflows (hard to achieve in Python due to mutability), smart cells, and other fresh ideas
* A more cohesive ecosystem - Nx, Scholar, Explorer, etc all play together, zero-copy and all, because they are the only players in town
Of course, there are also things that Python can do, that we cannot. The most obvious ones being:
* In Python, integration with C code is easier, and that matters a lot in this space. Python also allows C to call Python, and that's just not possible in the Erlang VM
* Huge ecosystem, everything happens in Python first
At the end of the day, what drives me is that the Erlang VM offers a unique set of features, and combining them with different problems have historically lead to interesting and elegant solutions. Which drives more people to join, experiment, run in production, and create new things.
[1]: https://phoenixframework.org/blog/phoenix-liveview-1.0-relea...
And then began adding an entire static type system to the language
* 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.
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.