Look at things like ebpf and uring for examples of meeting real needs with new development in the kernel.

I doubt that a LLM will be able to come up with the ideas, and implement these things without substantial prompting.

For the every day stuff. Yeah, sure. Though you'd be amazed how many strange corner conditions POSIX and Linux have even around "simple" things like pipes.

... Understanding the whole context may be beyond where we are today based on what I have seen from LLMs, there may day where they can come closer. But as the Klingons say: "Not today."