Understand that some of that stuff, especially P&P&Z is actually making fun of Austen. And volume of available material really is immaterial, this is the cinema world that has twice released 2 movies based on the same book nearly simultaneously (Haunting of Hillhouse by Shirley Jackson). And really if you want to talk about a veritable industry with tons of supplementary material that IS King. The guy is the Kiss of authors, he’ll greenlight any thing. An Amazon search on Dark Tower comes up with 8000 items and almost all of them actually are related in some way to King’s series.
Making fun of her in an affectionate way. Austen was a satirist/comic genius to begin with and would get a kick out of it. She made fun of Gothic novels the same way. There aure actually much more adaptations of King than Austen but a lot of them are obscure short story adaptations made for Tv or straight to video that very few people have heard of.