Ideas for a revival.

Mutare died long before the day of Armageddon. So, she is out of the picture. Here's a slightly modified plot suggestion: after Armageddon, after Gelu's death, some of the elves fled to the dungeons. There, they encountered the Swamp creatures, their enemies (from the second campaign of The Restoration of Erathia), who were also seeking refuge from the destruction underground. And from there, the story could develop in one of two ways: either the elves united with the Swamp creatures, or they defeated them and partially enslaved them, while the survivors fled even deeper underground.