I wouldn't say that it's unable to make a comeback, there is still a valid use case from my experience with it. The syntax, mixed-memory model, UFCS, and compilation speed are nice quality of life features compared to C++, and it's still a native binary compared to C# and Java. So if you're starting out with a new project from scratch there's not much reason not to beyond documentation reasons. And you can interface pretty easily to C/C++ as well as pretty much any other language designed for that sort of thing, but without a lot of syntax changes like Carbon.
I imagine that the scope of its uses has shrunk as other languages caught up, and I don't think it's necessarily a good language for general enterprise stuff (unless you're dealing with C++), but for new projects it's still valid IMO. I think that the biggest field it could be used in is probably games too, especially if you're already writing a new engine from scratch. You could start with the GC and then ease off of it as the project develops in order to speed up development, for example. And D could always add newer features again too, tbh.
You always have to compare ecosystems, not programming languages syntax on their own.
Another thing that Java and C# got to do since 2011, is that AOT is also part of the ecosystem and free of charge (Java has had commercial compilers for a while), so not even a native binary is an advantage as you imagine.
First D has to finish what is already there in features that are almost done but not quite.
TBH I don't necessarily think that ecosystem is what matters in every application, but it is necessary for most people, I agree. And I do agree with finishing a lot of the half-baked features too, but I'm unsure if the people maintaining the language have the will or the means to do that.
Do you have any other ideas about how D could stand out again?
It is what matters, as most companies pick languages based on SDKs, not the other way around being one pony trick and trying to solve everything with the same language.
That is why outside startups selling a specific product, most IT departments are polyglot.
For D to stand out, there must be a Rails, Docker like framework, something, that is getting such a buzz that makes early adopters want to go play with D.
However I don't see it happening on LLM age, where at a whim of a prompt thoughts can be generated in whatever language, which is only a transition step until we start having agent runtimes.
C#, Java and C++ have poor copies of the D features. For example, C++ constexpr is a bad design because a special keyword to signify evaluating at compile time is completely redundant. (Just trigger on constexpr in the grammar.)
C++ modules, well, they should have more closely copied D modules!
They might have, still they are good enough to keep people on those ecosystems and not bother at all with D, and tbe current adoption warts concerning IDE tooling and available libraries.
Unfortunately the opportunity window is gone now, and in the LLM age programming languages are becoming less relevant, when programming itself increasingly turns into coordinating agents.
I have a very naïve and maybe dumb question coming from someone who is used to scripting languages. It's about the `auto` keyword, while being a nice feature, why is it necessary to write it down ? Isn't it possible to basically say to the compiler : "Hey you see this var declared with no type ? Assume by yourself there is an `auto` keyword."
The various WIP features, and switching focus of what might bring more people into the ecosystem, have given away to other languages.
Even C#, Java and C++ have gotten many of features that were only available in D as Andrei Alexandrescu's book came out in 2011.