Will we go through local minima while on the path towards absolute upward progress? Of course we will. Right now we might be in a local minimum. Maybe we haven't reached the bottom of the current local minimum yet. Maybe we won't reach it during this generation. But we will get through it.
The other thing is that we simply can't predict societal progress simply by pointing to current trends and extrapolating to the next 5, 10, etc years. Think about the following:
70 years ago, there wasn't a single artificial satellite in the sky. 50 years ago, there wasn't a single personal computer in anyone's home. And 20 years ago, there wasn't a single smartphone in anyone's pocket. All of the above happened within a single human lifetime. I'm saying that it's taking shorter and shorter intervals of time for society to completely transform itself, and we simply can't know what the next transformation will be. For me, that's a prospect worthy of excitement instead of dread.