I've written 2 books. One complete, the other nearly complete in pieces. They're terrible, but that's that. If I dedicated myself to writing, I'd like to think I could at least become competent. Currently, like the majority of authors, AI would blow me out the water - and then some.
For the future, I'd like to think AI writing is policed. A kind of AI that monitors "cheating", which will determine what kind of percentage help authors have had. Think along the lines of chess. Real players kept in line by advanced analysis. This will keep skilled authors at the top and unskilled authors at the bottom. The proper way.
As for when the next gen AI writing assist tool goes on sale, I'll be first in line.