When people hear 'underclass' there's that mental image of food stamps and homeless shelters. I suspect though the society will converge to something similar to current status quo. We'll end up having our usual comforts, leisure, air travel, entertainment for the rest of our meaningless lives like in a handicapped Culture story. It is the path of least resistance for the dynamics explored in the article.

As a consolation AI existence will be just as meaningless (not that it cares). It will not be our scheming overlord but a tool that threw their master into existential crisis.