The article focuses on linguistic theories that regard natural language in a somewhat narrow sense: language as a cognitive phenomenon, language as a symbolic system, language as something that can be modeled and imitated by a computer. While those aspects are important, language is also a social phenomenon, something used for interaction among people for many different purposes.
Both traditional approaches to natural language—the cognitive and the social—face a challenge, because language is no longer used only for communication between human beings. What does it mean for linguistics now that human beings are increasingly using natural language to interact with computers? I don’t know the answer, but it’s a question that deserves attention.