Love the series and the ending.

I think the loop just shows the cross the gunslinger must carry for eternity. Death, but not for you gunslinger, never for you. He is destined to wander the path forever, being a good/white force in deadly opposition to the bad/red force. Roland is the Ying to the Yang and must always loop forever to protect us and he must grudgingly bear this heavy burden.

As for the Horn of Eld. That just shows that each level or life is different in some small way. I don't think the object is important just a glimmer of how and why there are many different realities. Also, on that note, I suspect the new Dart Tower movie is a continuation of the series. Instead of pissing us all off and not staying true to the series, King uses the next level/life to tell the saga. So when things aren't going the way they should according the books/Ka, the excuse is this is the next chapter in the loop. Don't be surprised when the movie starts off with Idris Elba holding the Horn of Eld.

Thanks for listening.