I do not believe there are many niche areas for web design anymore. The biggest niche area for design and layout, in my opinion, is UI/UX design and helping clients ensure their web interfaces are intuitive and easy to navigate. For the record, the idea of developing a great, easy-to-use interface has been part of web design for more than 25 years. Only within the last 10-12 years has acronym and label "UX" been applied to it.
For web development, which focuses on programming, scripting, back-end database operations, etc., I think the JavaScript frameworks are still popular and SQL programming and database optimization will never go away. Neither of those are really niche areas, but people are still getting paid a lot of money to provide those services.
I think the next biggest thing for web development (not necessarily web design) is the integration of generative-AI programs into web applications and interfaces.
