I'll just go ahead and say it....
It will not be a success. As much as a few of you are looking at the glass half full, I have no such illusions. As I said in an earlier post there is far too much material to cram in a single movie to make this even remotely digestible to the average movie goer. Unless you know the books, the whole concept of parallel universes, ageless wizards, cowboy knights, robots, Ka, Beams, (I could go on and on) will be lost on the vast majority. People will be saying to themselves "what the hell did I just watch?". Any of the Dark Tower taken out of the whole and context as we the Constant Reader understand it will be lost upon most.
As someone else on here pointed out, without the opening story of Roland chasing the man in black, there will be no "hook" to let people know they are in for one hell of a ride. How great would the culling of Tull have been for the first time on screen to set the pace and introduce the Roland we all know and love? The first encounter with Jake at the Waystation? The Slow Mutants? The encounter with Walter on the shore of the ocean? Ah, Discordia. So much potential.....I won't say lost. No. I'll have to say postponed. I believe someday, someone, somewhere will pull out their proverbial head and bring us that story to the screen.
In the meantime, we can only sit back and let this boil fester, pop, and slowly heal. Then after the memory of it fades I fully believe someone with honest love for the story, with the know how and clout, will step forward and do this justice. Someone like Jackson, who's true admiration of Tolkeins work led him to a phenomenally visual and mostly true to the book movie. (I'll forgive him the Hobbit as he tried to pass that torch off in the first place.)
That's the realization I have come to terms with. It just means more time. Barring I don't choke on a chicken bone or some other unfortunate untimely incident, I should be around to witness it.