That's what I think. Everything with his name on it these days is ghost written and aimed at being made into a cheesy sci-fi movie presentation of the week. I think he reviews the work, just the same way a master electrician signs off on the journeymen's work, but as long as the royalty checks arrive, he's retired.
I stopped reading him after Wizard and Glass in 1998. That was supposed to be his tour de force and it was even clear to Roland the Gunslinger that King was tired of writing.