I have not read the Bombadil discussion. I tend to avoid them and have been too sick to keep up anyway. However, most people misunderstand what the Dagor Dagorath is with respect to Tolkien's work. In the original Silmarillion conception, Turin Turambar was going to be resurrected at the end of Time to help the gods defeat Morgoth. He and Nienor would then become gods.

This story was connected with "The Second Prophecy of Mandos".

However, Tolkien abandoned the idea of "gods" (making Iluvatar the only god) when he gave up the idea of creating a full mythology and simply decided to focus on the Silmarillion stories as a legendarium of the Elder Days. He did eventually come back to the idea of Turin being resurrected, but only temporarily at the end of the First Age so that Turin could help fight in the War of Wrath. But this concept was never very fully developed and Christopher Tolkien did not incorporate it into the published SILMARILLION.

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Parma Endorion: Essays on Middle-earth, Revised Edition