It means that you should be careful to not judge too quickly. Because there are many examples in the past of people clinging to the status quo and refusing to believe that new technology could actually supersede human capabilities.
All i'm really arguing for is some humility. It's okay to say we don't know how it will go, or what capabilities will emerge. Personally, I'm well served by the current capabilities, and am able to work around their shortcomings. That leaves me optimistic about the future, and I just want to be a small counterbalance to all the people making overly confident predictions about the impossibility of future improvements.