Eden and Elidibus
I noticed that while we got the six elements done, it still hasn't really explained what Eden even is or what triggered the Flood of Light in the first place. It seems likely that Elidibus's plan with all these Warriors of Light is to eventually push conditions back to initializing the Eighth Umbral Calamity,

Given that Ryne and now Gaia are essentially retooling Eden into a terraforming system, I wonder if that's going to sabotage Elidibus' plans. If that is the case, perhaps we'll be facing him in 5.4 in the finale of the Eden raid, with 5.3 just having Sapphire Weapon trial.