Right, but I think any language that is "complete" is either dead, dying, or headed for a tiny niche (or already in a tiny niche). Can you think of any counterexamples?

The vast majority of languages are dead, dying or headed for a tiny niche. How many languages can you name that aren't? There can only be at most 3 languages with more than 25% market share.

Even Python is likely to die; in time. Most things do. Something will have to change first, at the moment it is doing great.

You seem to be arguing against something I didn't say. All I'm saying is that change is a sign of life, and that non-change is a sign of the opposite.

Go ye unto your tool shed, examine your spanner for signs of life, and you will have the possibility of gaining enlightenment - for you are correct in your argument.

C.

C is changing (C99, C11, C17, C2x). It is also increasingly relegated to niches like embedded and systems, though there's still a lot of other use.

Web development as well, as it turns out (compile to wasm).

Nothing is ever truly complete. Especially mediums of communication and construction, such as a programming language.