I would REALLY like to see these end game questlines open up the possibility of "going to the Dark Side" for characters. Some players just LIKE to play bad guys! And since this happens at end game doing so does not conflict with the original main story questline wherein we are all heroes. Maybe some of us just got tired of maintaining the illusion that everything is rainbows and kittens when in reality we're continually covered in blood.
Thus, these questlines should have very dramatic and opposing outcomes based upon player choices. While there are nearly numberless amounts of "gods" across the face of Nirn The Eight are pretty much universal and so let's go with a storyline where our character is confronted by one of them based on their class and is given a quest of, of course, amazing importance. While on the quest, they are confronted by the Daedric opposite of the god in question and given the option to subvert the quest and serve the Daedric Prince instead. I have deliberately chosen Divines and Daedric Princes we have not yet seen much of in ESO and who would be natural adversaries.
Sorcerer: Julianos (God of Wisdom and Logic )/ Hermaeus Mora (The formless Daedra of knowledge and memory, seeks to possess all that is knowable.)
Dragon Knight: Stendarr (God of Mercy and Justice )/ Boethiah (Deity of deceit, secrecy, conspiracy, treason, and unlawful overthrow of authority.)
Night Blade: Arkay (God of Life & Death )/Nocturnal (Deity of the night and darkness, the patron of all things secretive.)
Templar: Dibella (Goddess of Beauty and Love )/Sanguine (Prince of hedonism, debauchery, and the further indulgences of one's darker nature.)
What kind of skills and quest rewards would you like to see if ZoS were to implement these questlines? What kind of story arc would intrigue you and keep you engaged?
PAWS (Positively Against Wrip-off Stuff) - Say No to Crown Crates!