> What I'm mostly concerned about is not even economic, it's psychological. With nothing to do, people will not have purpose, and bored people are a gunpowder keg.

I'm not so sure about this one. The powerful in a society like the one you describe would surely know about that potential powderkeg and supply ample cheap entertainment to dull the edge. Then we'll have a society of mostly dull, idle, useless people with no purpose.

That's even more dystopian than your scenario, if you ask me.