In an interview about his upcoming film Rush, Ron Howard was asked about The Dark Tower. You can listen yourself below.
From The Empire Film Podcast:
Howard: The Dark Tower is something that we're still working on, and we've all sort of taken an agreed vow of silence about the progress, the headway, what we think our timetable is. I don't think I realized how much media interest there was in the title and how much excitement there was. It's a fascinating, powerful possibility, and even Stephen King acknowledges it's a tricky adaptation.
To be honest, from a financing side, it's not a straightforward, four-quadrant, sunny superhero story: it's dark; it's horror. That edge is what appeals to me, and the complexity of those characters is what appeals to all of us. I think Stephen King really respects that Akiva Goldsman and myself...that that's what we love about it, and that's what we want to try and get to the screen. So the answer is, it got delayed in our minds; it's never gone away. We're working on it, and he's very patient with us.
Akiva's just gone off and directed a movie, and I'm continuing to work, but the Dark Tower dreams -- the fever dreams -- are still with us. But we're not going to give it a timetable, because it was always a little bit over-reported in terms of when we thought the start date was, and then it was hugely disappointing when we didn't meet that date, and so forth. I don't think it's a project that really benefits from being scrutinized in that way.
Empire: I'm sure your vow of silence will cover it, but...Stephen King himself appears in The Dark Tower. Have you thought about how you might tackle that?
Howard: Yes! And I will admit that Stephen said, "I don't have to be in this." But that's not to say that he won't be!