There was a reason they buried Thorin Oakenshield with the Arkenstone. Not because he fought so hard to with it back. Not because it meant that his right to rule was divine. They buried him with it because the Arkenstone was the heart of the mountain and Thorin Oakenshield was the heart of his people. And as long as the heart of the mountain was there in it the mountain would never crumble. As long as Thorin Oakenshield was with his people in the mountain, his people would never crumble.