> We have to maintain everything, old and new, because it's all still critical, engineers have to learn everything, old and new, because it's all still critical.

I completely agree but maintenance is a maintainer problem, not the consumer or user of the package, at least according to the average user of open source nowadays. One of two things are come out of this: either the wheels start falling off once the community can no longer maintain this fractured tooling as you point out, or companies are going to pick up the slack and start stewarding it (likely looking for opportunities to capture tooling and profit along the way).

Neither outcome looks particularly appealing.

Yes, this just sounds like the run-of-the-mill specialization issue that is affecting every industry (and has been affecting every industry before AI). Web devs learn Javascript/Typescript/frameworks, "middleware" developers learn Rust/Go/C++/etc. to build the web development frameworks, lower-level devs build that, etc. There shouldn’t be a strict need for someone who wants to make websites or web technology to learn Rust or Go unless they want to break into web framework development or WASM stuff. But again, this is just over-specialization that has been happening since forever (or at least since the Industrial revolution).