Why Google’s algorithm is slowly making SEO agencies obsolete

There’s nothing new about questioning the future of SEO; people have been saying SEO is dead ever since it began. But with Google continually tweaking its algorithm in favour of a more natural approach, it’s difficult to see a long-term future, not so much for the practice itself (or at least the intent behind it), but for the agencies who live and die by the latest algorithm updates.
I think the question goes beyond whether SEO companies can survive or not, to how they adapt, what t