I think the technical specialty that will be most at threat from automation by AI would be the exact job that he authored has -- solutions engineers that build commodity cloud infra on AWS, Azure, G cloud, etc.
Look at progressions and range of abstraction between standard sys admin IT work to serverless deployments, especially with IaaC tools.
You can describe your architecture to chatGPT and it can spit out a CloudFormation YAML. It will be rudimentary and poor, but I could see a Gen AI tool offered by cloud providers where al you do is describe your app and then deployed infra on your behalf, and optimize form there.
Not trying to talk down on folks who do this type of work, but sharing my opinion on where I think the author is ultimately coming from.