Ask HN: What happens when there's nothing left to invent or discover?
There have been very long stretches of history in which general human progress was stagnant.
Productivity growth will eventually slow, given that we are limited in what we can do by the laws of physics.
Of course I could continuously rearrange superficial designs of things, which may give me an infinite number of things to do, but that doesn't increase productivity. There are a finite number of ways to do something in a more productive and efficient way than previous methods.
Given this, eventually we will reach a time when we can't make any more progress in the traditional sense.