I don't think it's at all guaranteed that future neural networks will grab continuity and context [in a meaningful sense, as opposed to basics like the character and place names being consistent and the context continuing to involve a murder and detectives] still less actually plot well. More importantly, for actual publishable writing as opposed to spam content AI has to do more than just start to grasp continuity and context, because every unpublishable human writer reaches that level, and most of them understand the much higher level of narrative arcs, characterisation and twists too. I don't think the cost of cash advances for no-name writers or lack of half decent unsolicited submissions to choose from is a big problem for publishers, is it? Surely 'time to fix not-irredeemably-flawed texts up enough to make them marketable' is in shorter supply...

Agreed that AI-assistive writing is pretty close to the point where it can save you the hassle of thinking up interesting ways of describing minor characters and locations, but of course when it reaches that level there are massive areas of content creation for AI companies which are more lucrative than novel writing and don't require further technological advances...