think about how in music, when an artist comes out with something original and awesome, and then everyone starts copying it and creating their own derivative works, like Jimi Hendrix or something.
Did Hendrix become useless? Did everyone end up thinking he sucks or something? No, he is even more revered, as the originator of a new type of sound that probably created multiple genres
The same thing applies here. Originality will be valued and even empowered as extrapolation and development off of it can increase in speed and quality in the case you mention
True, but some nuance is that a LOT of artist/creative types lean exclusively on the mechanical skill needed to create, without anything really much to say. They also very frequently copy other's styles, etc.
I'm not defending AI pumping out crap, but this also shows a lot of folks don't have much to offer beyond the mechanical aspects and we shouldn't glorify churning out stuff by hand as high art either.