User blog comment:DirgeOfCerberus111/An Alternate Universe? Let the heresy begin!/@comment-3562230-20110824133522

If the Eldar don't fall, Slaanesh would not be created, and the eye of terror would not exist. No Dark Eldar either. With the Eldar at full strength, Chaos (without Slaanesh) wouldn't be as big of a threat.

There would be an epic Imperium vs. Eldar struggle. Maybe they would finally be smart and form an alliance. Together they could stop the necrons and tyranids.