In the future GANs will replace all of human creativity so much so that humans will spend all of their creative outlets on training GANs and using GANs to do the creation for them.
Huamns can produce novel artworks that a computer cannot, usually with more control over the intagibles like creativity and the fundamentals like drawing and perceiving the world.
The same could be said of humans. A lot of humans would say a random piece of quality GAN-generated art is a creative work. They may not say so if they first looked at every piece of training data that went into it. But then, they might not do the same if they looked at every piece of art produced and viewed by a given human artist previously.
As a thought experiment, if the line in the sand is whether a computer can generate a piece of art that people think is creative, even with full knowledge of every piece of training data- I think that's not at all difficult to overcome long term. Possibly even with current models.
When that happens people will start training GANs with GAN data.
It will become a self feeding loop with humans only curating data.
Of course even the curating of the data is ripe for automation via ML.