You know, I actually had an idea related to TDT that I wrote about...no one will ever read it in its entirety, for fear of being sued for plagiarism, but the basic premise was about Roland renewing his Quest, only this time with the knowledge of the previous attempts to complete it, and in the end (of my version), the Gunslinger learned this:

It is not, he surmised, the writer. Nor is it the Creator, although it is of him. It is not even the sainted flora. No, thought he, the great spoke upon which the wheel of the Tower spins is none of these things. The Dark Tower is the apotheosis of the one thing he could never truly appreciate, could never comprehend, before this very moment, this epiphany.

Imagination.

Thus thinking, thus understanding, at long last, the Gunslinger lay down his guns at its door. He raised the ancient Horn and blew, trumpeting for all that he was worth, trumpeting for his father, for his lost friends, for his quivering, mortal soul, which he now felt stir in a vague sense of ecstasy which he had never known before.

He imagined Gilead, shining in its beauty. He imagined his father, Steven, proudly surveying all that he commanded. He imagined Cort, and he imagined Cort blessing him for his conquest; but that was not the true conquest, nay, the true conquest lay here, in the amazing sight which spread before his astonished, gleeful bombardier's eyes.

All-World was reviving.

The Beams were renewed, the Baronies restored, the lushness of all that had ever been in his time, intact. The Crimson King, who thrived solely on the insanity that is loss, simply was no more.

Reveling in his newfound glory, Roland Deschain clutched the Horn to his breast and cried.