at this point this is a HL3 situation and it's better if he never finishes the series. it will never live up to expectations. leave it be. if you enjoyed the story so far, celebrate that and move on. it's about the journey, not the destination.
He's never finishing the series. He's going to be 76 in a month, he still has probably most of Winds to finish after 13 years, the math doesn't work out to getting A Dream of Spring, let along the fact that this story is way too big to satisfactorily conclude in 2 books at this point, and even if it could be done it would be complex and difficult and take longer than usual.