All languages stop evolving at some point. C isn't there yet, but there are many dead languages that people only use because a lot of things are already written on it, and nobody wants to change anything.
So why does that mean Rust will be abandoned in a few decades?
Do you think there will be a trend "back" to using C or C++ for systems programming? I would bet against it. I do believe, by the way, that C has stopped evolving (which is good) and that C++ should stop evolving as well.
Or do you think the replacement of old languages by new ones will accelerate? So in 30 years most systems programming will be done in a language that doesn't exist yet? Maybe not done at all in a "programming language" as we have today?
Or do you think Rust is clearly losing out to some other new languages for systems programming, such as Zig, and will never be popular enough in the first place to enter the "slowly dying legacy" regime?
You don't need a "trend back to using C++". C++ usage is still growing by leaps and bounds. The number of people picking up C++ for professional use, in any short interval -- used to be two weeks, now a bit longer -- is more than the total number who are coding Rust in production. That will be true for a long time.
