This is what the moderator of King's board said:
Another one will be coming out in a month or so but can't release details yet.
This was posted last month and she later clarified that it's not part 2 of In the Tall Grass she's talking about by saying:
Question: That other story you mentioned that will be out in a month or so... is that part two of In The Tall Grass?
Moderator: It's not the second half--that's still the same story, not a different one.
So, there you have it. More King stuff coming. And when you visit Charnel House don't forget to check out Kev's books, OK? Good.