I was sitting in school & I thought of this (in my eyes) great idea for the next legendary questline, personal progression, for example, You have a quest to obtain 20 items, the 20 items are "dropped" by doing something personal on a boss, so for example, your raid team starts the encounter & if you're on the right quest a "portal(or anything else) could open just for you, you have to go in there & do a personal challage.
Looking at how well you beat the challange, the more items you obtain to complete your quest, it would make legendary quests require much more personal skill than it does at the moment.
I know its probably explained terribly bad, but I'm horrid at writing stuff & I apologize for anyone not understanding what I meant.
Note that my Idea is based on the Norushen encounter with the Tank Healer & DPS challanges.