I don't think an area such as AI can be called a specialist area. There is simply too much breadth once you start getting into the nitty gritty of building an AI product. If your goal is to be a well versed product builder in AI, then you need to master software engineering, building deep learning models, training on large clusters, deploying on the edge - man it's a lot.

A data scientist or a deep learning engineer - yes that's somewhat of a specialist role. It again depends on what you want to accomplish. If your goal is to research deeply in one area such as NLP then yes that's a specialist role.

OR,

If your focus is purely on infra, like building and enhancing Pytorch or Tensorflow, yes that's specialist knowledge in fine tuning a loss function etc or building a new loss function altogether.

As far as I am concerned, yes I do sometimes wish that I had stuck to one breadth area such as AI or mobile app development or AR/VR instead of somewhat dabbling across all these areas. No regrets though.