It’s probably worthwhile to consider both fiction and non-fiction and literature. I’d imagine fiction in particular is dying but literature and non-fiction are selling as well or better than historically, which means not mainstream but sustainable to the (very) limited count of authors capable of making it, literature in particular.

I’m not concerned if we don’t uncover the next Stephen King (he’s got a few great books though!) so long as the next Pynchon is published.