I wonder what Bungie is going to do with Savathuun and her Lucent Hive. They must still have a part to play. They'd be great allies, if they could stop acting like typical Hive for five minutes and have Savathuun start acting more like a strategist and stop being a deceiver who can't be trusted.
The Cabal and Eliksni have joined us, now all we're missing is a Hive and Vex faction.
Edit: Because Savathuun doesn't have a worm to feed anymore, she doesn't have to follow her nature. She CAN pick a new destiny for herself. Bungie just has to get on top of writing her redemption story.
-
I personally suspect that Savathun will have a role to play in defeating Xivu Arath. She may have even dropped us a hint on how to do it too. Before she became a Lightbearer, she allowed herself to be imprisoned in the crystal structure by Mara as they worked to remove her worm. We could, theoretically, do the same to Xivu Arath. Basically starve the Hive god of War from receiving her tribute by isolating her and let her worm destroy her.