I have no fears of being completely unemployable in my 50's or 60's. But in my mid-40's now, I'm already losing interest in web development as a particular niche. A lot of students and junior developers might not be completely aware that there's even a difference, a subset/superset thing there.
Web development is so accessible, anyone can self-teach. It's not so common to learn EAI, ETL, large-scale batch processing or data streaming, etc by way of personal GitHub side projects. It's basically a long, slow process of getting hired for roles that you're not 100% ready for, at companies with those sorts of needs, and growing into it over time.