I like the idea of using the Mortis idea from TCW and also in "The Fate of The Jedi" and "Crucible" and "Dawn of the Jedi". I can see a group or one person who is like a grey Jedi or like the Jedi from "Dawn of the Jedi" they used both dark and light side of the force for balance. The person or group is unhappy with the way the Jedi and Sith have been doing things causing an unbalance in the force for too long and they show up to deal with both sides. I would love to see this both Jedi and Sith having to team up and fight this Mortis group or person and each other as well. We can have the son of Luke, Ben and his Sith love interest Vestara play out as well as many great characters on all sides. The end of the Luke Skywalker legacy could be him taking control of this Mortis group and becoming the Father and he will bring balance to the force, thus fullfilling the phrophecy his father started.