If low end graphic artists can 10x their output there will not be a need for nearly as many graphic artists, regardless of how many new markets they may think exist. So it will certainly replace many of them.
Nah, it happened with IT. We now have tools and frameworks that allows developers to be 5x, 10x more productive than 30 years ago. There are more developers now than ever. The demand is higher than ever as well.
You might be wrong: it could be that the increase in productivity lowers cost and in turn increases demand. See Jevon's Paradox.
This hasn’t been the case for many tech developments over the decades though.