Ask HN: What skillsets/stacks will keep me employable over the next 5-10 years?

I’ve noticed that my particular “niche” within software development has, especially over the past two years, become extremely saturated. At the same time, the actual market need for this niche seems to be slowly decreasing.

I’m a senior dev and can still get gigs, but nowhere nearly as easily as I could 5 years ago, despite having 5 more years of experience.

I’m wondering if there are a few particular tech stacks/technologies that would be worth focusing on and becoming an expert in to stay employable over the next 5-10 years.

Yes, I know it’s good to be a generalist, and I am, but employers seem to prefer to hire “experts” in particular domains.

Specific answers would be appreciated. “Focus on AI” and the like aren’t particularly helpful, though of course I appreciate the input!