The point was that so much has changed in the previous ~80 years that I don't think it's ridiculous to think things will be radically different ~80 years into the future.
Barring universally available, and highly advanced nanotech, it's ridiculous to think that all diseases will be "tackled" in ~80 years. In that same time frame it's much more likely that we'll be tackling issues of how to maintain a semblance of civilization, not achieving utopia.
