In chapter 908 the Five Elders kneel before Im, requesting that the figure share with them the name of the “light” that needs to be extinguished from history.
Inside the Room of Flowers, an attendant tells Im that everyone has arrived. Im heads out, leaving behind the torn-up bounty posters of Luffy and Blackbeard as well as a picture of Shirahoshi with a sword plunged into it and carrying a picture of Vivi. But why and what is the LIGHT that the Gorosei are mentioning?
I believe that the LIGHT is a reference to a person who overall has the willpower, strength and skills and sheer determination to lead others.
As we have seen, Luffy has both the power, willpower and sheer determination to lead and a knack for attracting others, Blackbeard has the power to destroy and the uncanny ability to plan, Shirahoshi is the Ancient Weapon Poseidon and has will to follow in her mother’s footsteps.
Shiraoshi, Vivi, Luffy and Blackbeard are the 4 LIGHTS that give Imu-sama and the Gorosei the most problems because they can change and lead.
Both Luffy and Blackbeard carry the Will Of D. while Shirahoshi and Vivi are connected to 2 of the 3 Ancient Weapons; this will lead to Im-sama telling the Gorosei to eliminate/extinguish the lights of Vivi and Shirahoshi. I believe that the Gorosei will order the CP0 to eliminate Shirahoshi and Vivi and brand them as traitors to the World Government and the Gods. During this time i believe CP0 will kill Don-Quixote Mosgard as he will attempt to save them.
This will lead to the appearance of Sabo and the Revolutionary Commanders as it would be time for them to start their operations. After the events of the Reverie we will see Vivi and Shirahoshi and the others allies leave with the Revolutionaries!
The Gorosei will announce to the world that Alabasta and Fishman Islands are allies of Monkey D. Dragon and this will bring the World Government to summon a Buster Call in order to destroy Alabasta and Fishman Islands.
*Theory by Man of Theory