… Aslan spoke, he no longer looked straight at them like a lion; but what began to happen next was so great and beautiful that I cannot describe it. For us, that was the end of the story, and we can most truly say that they all lived happily ever after. But for them, this is just the beginning of the real story. All their life in this world and all their adventures in Narnia had been but the cover and title page of a book: now at last they had begun the first chapter of the great story. No one in the world has ever read this great story, this great story that will go on forever: each chapter is more exciting than the previous one.
——Excerpted from the last paragraph of "The Chronicles of Narnia: The Last Battle"
So the Narnia stories never have a final ending.
Taking over the HP of the previous book, I may go - The Chronicles of Narnia: The Last Battle - Game of Thrones Seasons 7 and 8 - The Lord of the Rings/The Lord of the Rings
I'll keep it here, I've finished writing the first one next door and I'm still working on it.