Finally read this… finished it last night. Kind of strange to realize that I’ve been following this series for more than half my life!
I interpret the horn on his belt as a sign that each time he learns something important, the Tower (or ka, or whatever) kind of “throws him a bone” on the next loop… in this case, he realized before entering the Tower that he should have picked up the horn at Jericho Hill, so this time the Tower fixed things so that he HAD done so. In this fashion, his lessons can stick with him even when his memory resets.
Not that I think the horn itself is so vital (the door DID open without it, after all), but Roland’s concern for it (or lack thereof) shows something about his attitudes. It’s an important relic of the line of Eld, and Roland’s disdain to bother picking it up was a symptom of his greater problem. Next time through, his concern for the horn shows how much his general ability to CARE has improved. Not only can he care about people… he can care about THINGS that mean something to people.
(Now that I think of it, wasn’t this part of Superman’s development in “Kingdom Come”?)
Aside from letting King use the final line, the “back in the desert” bit works in the sense that soon after this point, Roland will draw the first member of his new ka-tet (Jake or an analog thereof). In a sense, this final ka-tet is Roland’s “final exam”: the way he deals with them through the troublesome events which follow is the behavioral sample upon which his moral development will be judged by the Tower.
Presumably, this iteration of Roland will tell the man in black that he can damn well wait outside the cavern while Roland pulls his young sidekick to safety!
Roland’s completed development will probably involve being sufficiently mission-oriented to save the Beams, but sufficiently humane to realize afterward that the job is done and it’s time for everyone to start picking up the threads of a normal life.
As in real life, it’s important to be able to work toward a worthwhile goal, but it’s also important to know when to quit. Failing the former makes you useless to those around you, failing the latter makes you, at best, equally useless, or worse, a danger (as Roland certainly has been to those around him!)
In such a case, Roland will abandon the Tower once he realizes that saving the Beams has accomplished his goal (saving the universe, stopping the world from moving on, etc.), and thus will never get to the room at the top of the Tower.
Mind you, this won’t necessarily be a happy ending for everybody. Jake and Eddy (or their analogues in this loop) may still be killed in action. A “fixed” Roland, however, will be able to realize that there’s been as much dying and suffering as circumstances require, and it’s time to stop before he causes any more, NEEDLESS, pain to his remaining friends.
This all seems to fit pretty well with the general trend of the series, as Roland has gone from being a soulless Terminator to being a man capable of sitting down and crying over the death of an animal. In this sense, I agree with King that the ending as written truly IS the ending that HAD to be written. A character is supposed to grow and change in a story… this character just needed a couple more cycles through the mill than most!
