If you haven't caught up with the recent lore reveals the Ancients are basically the ones that introduced The Corruption and are the primary antagonists of Ashes of Creation.
Surely there's a rebel, or rebels, among the Ancients that seeks to work against them and thus with you to reclaim the world.
To make a comparison with World of Warcraft, even the 'evil' races had factions among them that would work with the Horde or Alliance. Primary examples being the demons working with Illidan and of course the Forsaken undead that works with the Horde.
Even the Dreadlords that seem to be born evil or something work against each other from time to time. Whereas the Ancients in Ashes of Creation are said to have developed a strong sense of pride and ambition that's not exactly evil and would also cause what I've suggested which is a rogue faction.
I'm not expecting them to become a playable race but a faction you can work with and raise reputation and rewards with. They wouldn't necessarily be on your side per say but you can learn to work together regardless.