I think I would rather see the emperor title go and be replaced with commander. So that there are 3 emperors (now called commanders) for each side regardless of success. These commanders would be given tactical privileges as well as passives. Tactical privileges would include dropping respawn camps (with CD, duration, and cast time), reinforcing a keep, distribution of resources, campaign announcements etc. The commander would be given a group of set pieces that he can use or place strategically.
Regarding how the commander is chosen I envision something like Tera where the commander is manually chosen by his worth. Though I think that that there should be a default election system that would elect a commander automatically by performance should no one cast a vote. (along with the ability to refuse election) It would provide a check and balance between voting and ability.
It would be a system that made emperors (commanders) a position of leadership rather than convenience of passives.