It's interesting that he lists a number of historical precedents, like the invention of the calculator, or the mechanization of labor in the industrial revolution, and explains how they are different than AI. With the exception of chess, I think he's wrong about the effects of all of them.
For instance, people did lament the invention of calculators, saying it would harm kids' ability to do mental arithmetic. And it did. People also said that GPS navigation would hurt people's ability to use a map, or create one in their heads. And I'm old enough to say: it absolutely did. People (in aggregate) are worse at those skills now.
Fortunately for us, we replaced those skills with technology that allowed us to do something analogous to them, but faster and more easily.
The question is: what are the second- and third-order effects of losing those skills, or not learning them in the first place? Is it crazy to think that not memorizing things because we can access printed (and digitized) material might have larger, unforeseen consequences on our brains, or our societies? Could mechanizing menial labor have induced some change in how we think, or have any long term effects on our bodies?
I think we're seeing—and will continue to see—that there are knock-on effects to technology that we can't predict beforehand. We think we're making a simple exchange of an old, difficult skill for a new, easy one, but we're actually causing a more far-reaching cascade of changes that nobody can warn us of in advance.
And, to me, the even scarier thing is that those of us who don't live through those changes will have no basis for comparison to know whether the trade-off was worth it.