I think the modern definition of art is that art is anything that the observer perceives as art.
"and in fact they already are, but (2) there is still going to be a person who will need to use his or her personal taste to filter out the bad from the good, which might be what is going to replace the old way of creating things from scratch, e.g. with pen and paper."
No. Currently AI are synthesizing extrapolations from existing data. They can paint like van Gogh only because they have sufficient samples of the van Gogh style to learn the style transfer. Currently you still need a human to invent the style, at least.
On the other hand, once a style is invented, it's a matter of taste I suppose where the border lie. Ancient painter masters did hardly paint everything by themselves. The most prolific were more like Walt Disney or Damien Hirst who employed and employ legions of workers to implement their vision, and the artist merely signs off sufficiently high quality work.
So, I suppose you are wrong and correct at the same time.
https://qz.com/790523/daddys-car-the-first-song-ever-written...