Insane people will still create new tech stacks for fun just like they always have.

There will always be industries that require auditable code, so some things will need to be human-readable until we trust AI to audit code that's written by AI. I imagine that's a long way off, simply because no one will trust people not to use "AI wrote it! I had no idea!" as a way to get dodgy code past an audit.

I think it's likely that we'll invent new languages for AI to use because there's probably things that AI could take advantage of that humans wouldn't need or maybe even understand. To start with that's likely to be something around token efficiency but there's probably more interesting things to invent than that. Who knows. It's early days.

Will we ever truly give up human-written code though? That's unlikely. Writing code is fun, so people will always do it. Kind of like people building wooden furniture or build their own boat. Machines do it better, but that's not always the goal.