It’s not just about if a LLM could replace you, if a LLM replaces other enough other programmers it’ll tank the market price for your skills.
Why is it that you feel that you couldn't make stream processing that works for your use cases? Is it also that you couldn't do it after some research? Are you one of the juniors/mids that you refer to in your poost?
I'm trying to understand this type of mindset because I've found that overwhelmingly most things can be done to a perfectly acceptable degree and often better than big offerings just from shedding naysayer attitudes and approaching it from first principles. Not to mention the flexibility you get from then owning and understanding the entire thing.