Futile is much too strong of a word. I'm a white male, got a PhD in history, and ended up getting a good TT job in my first year on the market. Was I lucky? Undoubtedly. But some of the pessimism about history phds really is unwarranted in my view, for the reason the author mentions toward the end. I think the field has a strong future personally. It is just looking like the 80s through '00s was an enrollment high point. Doesn't mean there are no jobs left, or good work isn't being done.
On the other hand, I fully concede that, for my history and CS dual major students, I'd agree that it's be a bad idea to get a PhD in history if you have the skills and inclination to get a CS degree or a job at FB/Google/etc instead.